2025 CF Forging 49

Manufacture

Lower Receiver Calculation Results and

Equipment Selection

Based on the settings mentioned above,the upper

receiver is simulated using the deform software,and

the results are shown in Figures 7,8,and 9.The

appropriate equipment is selected based on the

results,as shown in Table 2 below.

Quality Issues and Solutions

Product Situation

There are 3 batches of forgings for both the upper

and lower receivers that have undergone the forging

process.

Upper Receiver Pre-forging

The first pre-forging of the upper receiver:The bar

material was heated in the heating furnace at 510°C

for 0.5 hours and then forged with 45kJ of energy.

The result was that the forging flash exceeded the

flash bin,and the die did not close.Solution:Deepen

the die flash bin depth.

The second pre-forging of the upper receiver:The

bar material was heated in the heating furnace at

Figure 6 Finish forging:Forming force F=766t,

Energy E=14.1kJ

Operation Cutting Size Heating Pre-forging Trimming Heating finish forging Trimming

Parameters φ48mm×170 430℃ / / 430℃ / /

Equipment Disk Saw Resistance Furnace Electric Press punch Resistance Furnace Electric Press punch

Numerical Simulation / / F=707t E=43.3kJ / / F=766t E=14.1kJ /

Final selection / / 1000t 200t / 1000t 200t

Table 1 Upper receiver simulation parameters and equipment selection table

Operation Cutting Size Heating Blanking Trimming Heating Pre-forging Trimming Heating Finishforging

Trimming

Parameters 60mm×40mm×180mm 430℃ / / 430℃ / / 430℃ / /

Equipment Disk Saw Resistance

Furnace

Electric

Press punch Resistance

Furnace

Electric

Press punch Resistance

Furnace

Electric

Press punch

Numerical

Simulation / / F=836t

E=36.9kJ / / F=724t

E=15.8kJ / / F=928t

E=11.1kJ /

Final selection / / 1000t 200t / 1000t 200t / 1000t 200t

Table 2 Lower receiver simulation parameters and equipment selection table

50 Forging 2025 CF

Manufacture

510°C for 0.5 hours and then forged with 45kJ

of energy.The result was that the bar material

temperature was too low,and the forging had cracks.

Solution:Increase the heating furnace temperature

and extend the heating time.

The third pre-forging of the upper receiver:The

bar material was heated in the heating furnace at

530°C for 1.5 hours and then kept at 510°C for

0.5 hours.It was forged with 32.8kJ of energy.

The result was that the bar material length was not

enough,making it difficult to position,and some preforged heads were not fully formed.Solution:Adjust

the positioning to be closer to the forging head

(Table 3).

Upper Receiver Finish forging

The first finish forging of the upper receiver:The

forging was heated in the heating furnace at 510°C

for 0.5 hours and then forged with 24.8kJ of energy.

The result was that the heating die used diesel

combustion heating,causing the forging surface to

blacken.Solution:Deepen the flash bin depth and

ensure died closure.

The second finish forging of the upper

receiver:The forging was heated in the heating

furnace at 510°C for 0.5 hours and then forged with

24.8kJ of energy.The result was that the die release

agent used graphite,causing the forging surface to

Figure 7 Roughing:Forming force F=836t,Energy E=36.9kJ

Figure 8 Pre-forging:Forming force F=724t,

Energy E=15.8kJ

Figure 9 Finish forging:Forming force F=928t,

Energy E=11.1kJ

Batch Energy/kJ Heating Method Issue Solution

1 45 510℃0.5h Flash exceeds bin, die does not close Deepen flash bin depth, ensure mold closure

2 45 510℃0.5h Low temperature causes cracking Increase heating temperature, extend heating time

3 32.8 530℃1.5 h

510℃0.5 h

Bar material length not enough,positioning difficult,

pre-forged heads not fully formed Adjust positioning, increase bar material length

Table 3 Upper receiver pre-forging

2025 CF Forging 51

Manufacture

blacken.Solution:Use aluminum alloy-specific died

release agent.

The third finish forging of the upper receiver:The

forging was heated in the heating furnace at 530°C

for 1.5 hours and then kept at 510°C for 0.5 hours.It

was forged with 31kJ of energy.The result was that

multiple forgings and die release agent spraying led

to slag accumulation inside the died.Solution:Clean

the slag after forging (Table 4).

Lower Receiver Roughing

The first roughing of the lower receiver:The

bar material was heated in the heating furnace

at 510°C for 0.5 hours and then forged with

24.1kJ of energy.The result was that the lower

receiver's roughing died lower die did not have an

ejection mechanism,causing adhesion to the died.

Solution:Add an ejection pin to prevent adhesion.

The second roughing of the lower receiver:The

bar material was heated in the heating furnace at

510°C for 0.5 hours and then forged with 24.1kJ

of energy.The result was that the forging flash

exceeded the flash bin,and the died did not close.

Solution:Deepen the died flash bin depth to ensure

died closure.

The third roughing of the lower receiver:The

bar material was heated in the heating furnace at

530°C for 1.5 hours and then kept at 510°C for 0.5

hours.It was forged with 24.1kJ of energy.The result

was uneven furnace temperature,with some sharp

corners not fully formed.Solution:Add padding to

prevent the bar material from direct contact with the

furnace wall (Table 5).

Lower Receiver Pre-forging

The first pre-forging of the lower receiver:The

forging was heated in the heating furnace at 530°C

for 2 hours and then forged with 31kJ of energy.

The result was that the heating furnace could not

ensure uniform temperature,causing the bar material

temperature to be uneven.Solution:Adjust the

positioning of the bar material.

Batch Energy/kJ Heating Method Issue Solution

1 24.8 510℃0.5h Surface blackening due to diesel heating Use gas (propane or natural gas) heating

2 24.8 510℃0.5h Surface blackening due to graphite mold release Use aluminum alloy-specific mold release agent

3 31 530℃1.5 h, 510℃0.5 h Slag accumulation in mold Clean slag after forging

Table 4 Upper Receiver finish forging

Batch Energy/kJ Heating Method Issue Solution

1 24.1 510℃0.5h Adhesion due to no ejection on lower die Add ejection pin to prevent adhesion

2 24.1 510℃0.5h Flash exceeds bin, mold does not close Deepen flash bin depth, ensure mold closure

3 24.1 530℃1.5 h, 510℃0.5 h Uneven furnace temperature, sharp corners

not fully formed Add padding to avoid direct contact with furnace wall

Table 5 Lower Receiver Roughing

52 Forging 2025 CF

Manufacture

The second pre-forging of the lower receiver:The

forging was heated in the heating furnace at 530°C

for 2 hours and then forged with 31kJ of energy.The

result was adhesion to the upper died.Solution:Heat

the upper died to a higher temperature.

The third pre-forging of the lower receiver:The

forging was heated in the heating furnace at 530°C

for 1.5 hours and then kept at 510°C for 0.5 hours.

It was forged with 31kJ of energy.The result was

that the heating furnace could not ensure uniform

temperature,causing the forging temperature to be

uneven.Solution:Manually heat the forging with a

torch after taking it out (Table 6).

Lower Receiver Finish forging

The first finish forging of the lower receiver:The

forging was heated in the heating furnace at 530°C

for 2 hours and then forged with 40.8kJ of energy.

The result was slight bubbling on the forging

surface.Solution:Heat the forging at 530°C for 1.5

hours,then cool and hold at 510°C for 0.5 hours.

The second finish forging of the lower

receiver:The forging was heated in the heating

furnace at 530°C for 1.5 hours and then kept at

510°C for 0.5 hours.It was forged with 40.8kJ of

energy.The result was that the draft angle was too

small,leading to frequent adhesion to the died.

Solution:Modify the died to increase the draft angle.

The third finish forging of the lower receiver:The

forging was heated in the heating furnace at 530°C

for 1.5 hours and then kept at 510°C for 0.5 hours.

It was forged with 40.8kJ of energy.The result

was slight bubbling on some forging surfaces.

Solution:Do not manually heat the forging with a

torch for too long (Table 7).

Effectiveness of Measures

After the aforementioned adjustments,a new

batch of forgings was produced through the process.

The forgings after forging are shown in Figures 10

to 14:

Batch Energy/kJ Heating Method Issue Solution

1 31 530℃2h Uneven temperature in furnace Adjust bar material positioning

2 31 530℃2h Adhesion to upper die Heat upper die to higher temperature

3 31 530℃1.5 h, 510℃0.5 h Uneven temperature in furnace Manually heat forging with torch after removal

Table 6 Lower Receiver Pre-forging

Batch Energy/kJ Heating Method Issue Solution

1 40.8 530℃2h Slight bubbling on surface Heat at 530°C for 1.5 hours, then cool and hold at

510°C for 0.5 hours

2 40.8 530℃1.5 h, 510℃0.5 h Frequent adhesion due to small draft angle Modify died to increase draft angle

3 40.8 530℃1.5 h, 510℃0.5 h Slight bubbling on surface Avoid prolonged manual heating with torch

Table 7 Lower Receiver Finish forging

2025 CF Forging 53

Manufacture

The forgings are well-formed,with dimensions

in line with drawing standards,good surface

quality,and no folding,cracking,or overburning.

The subsequent machining of the forgings met the

expected goals.

Conclusion

This document detailed the problems encountered

during the forging process of aluminum alloy upper

and lower receiver forgings and their corresponding

solutions.The effectiveness of the measures was

verified through actual production,which has

significant reference value for peers in the forging

industry for the production and design of this type

of forging in the future.

Figure 11 Upper Receiver Finish-forging

Figure 12 Lower Receiver Pre-forging

Figure 13 Lower Receiver Pre-forging

Figure 14 Lower Receiver Finish-forging

Figure 10 Upper Receiver Pre-forging

54 Forging 2025 CF

Die & Tooling

Research on the Forging Die Warehouse

Picking System Based on Electronic Tags

Wang Yuguo, Liu Zikang · Nanjing Institute of Technology

Xie Bin · Nanjing Kangni Precision Machinery Co., LTD

The adoption of digital, networked, and

intelligent technologies has significantly

impacted the efficiency of traditional

die warehouse management systems in forging

factories. These outdated methods hinder the daily

operational performance, highlighting an urgent

need for transformation and modernization. The

emergence of Internet of Things (IoT) technologies

and the advancement of intelligent warehousing

systems have brought about a shift towards frontend automation. The use of remote-controlled

electronic tags to replace traditional paper data cards

has become the prevailing approach. For instance,

intelligent picking systems are now widely applied

across various industries, demonstrating their broad

range of potential use cases.

(1)E-commerce warehousing industry: in the

e-commerce industry, where order volumes are high

and diverse, electronic tag-based intelligent picking

systems can significantly enhance order processing

speed and accuracy, thereby meeting the growing

demand for rapid delivery.

(2)Express logistics industry: In the express

logistics industry, electronic tag-based intelligent

picking systems facilitate the sorting and

categorization of parcels, thereby improving both

sorting efficiency and accuracy.

(3)Food packaging industry: In the food

processing and packaging industry, electronic tagbased intelligent picking systems can be employed

to streamline the selection of raw materials and

packaging, enhancing production efficiency and

maintaining higher hygiene standards.

(4)Pharmaceutical Industry: In the pharmaceutical

sector, electronic tag-based intelligent picking

systems can be employed for the loading and sorting

of drugs, ensuring both the accuracy and safety of

the drug selection process.

(5)Manufacturing industry: In the manufacturing

sector, electronic tag-based intelligent picking

systems can be applied to parts picking and

assembly processes, thereby enhancing production

efficiency and improving product quality.

Despite the widespread application of electronic

tag technology and intelligent picking systems

in various industries, there is limited research on

their use in forging die warehouse management.

Therefore, this study addresses the practical needs

of managing a forging die warehouse, focusing

on business requirements, functional analysis,

hardware selection, and algorithm development.

The research is based on the implementation of an

intelligent picking system for forging dies using

electronic tag technology.

System work flow and Functional Analysis

The work flow of the electronic tag-based

intelligent picking system in the die warehouse in

the forging production process is shown in Figure

1. First, the factory's manufacturing execution

2025 CF Forging 55

Die & Tooliing

system (MES) issues the production order. Based

on the requirements of the forging process, the field

operator submits a tool borrowing request. The

tooling warehouse administrator then creates a tool

borrowing list via the tool management information

system and generates a QR code for the list.

Then, by scanning the QR code on the die

assembly list, the system facilitates information

interaction, triggering signals to the warehouse

identification device system. These signals are

transmitted to the electronic tags on the shelves,

causing the tags to illuminate and display the

required number of dies along with other relevant

information. Finally, warehouse personnel complete

the die picking process and press the confirmation

button to reset the status of the electronic tags.

Based on the analysis of the forging die warehouse

business process and its requirements, the library

location marking system is designed.

Accessibility feature

The system is designed to accommodate various

user roles, including forging line operators, die

store administrators, and system administrators.

Users are required to authenticate themselves by

entering their usernames and passwords upon

logging in. Different roles have access to different

system functionalities: production line employees

and die store administrators can manage the daily

operations of the die warehouse, while the system

administrator is responsible for overseeing system

logs, role permissions, and forging production data,

among other tasks.

Business Function

Based on the contents of the die assembly list, the

system quickly locates the shelf positions of the dies

specified in the list and transmits this information

via the factory’s local area network (LAN) to

the electronic tags. The tags light up, enabling

easy identification of the inventory locations, and

simultaneously display the number of dies to be

borrowed. Once the dies are sorted, the warehouse

operator presses the confirmation button to reset the

electronic tag status and update the die inventory

status.

Integration with other systems

The electronic tag-based intelligent picking

system is integrated with the forging die

management information system, the manufacturing

e x e c u t i o n s y s t e m ( M E S ) , t h e e m p l o y e e

management system, and other relevant systems.

Die Usage Information

Data Storage

MES

System

Storage Location

Identification

System

Intelligent Lighting

System

Warehouse

Manager

Die

Borrowing

Print Died Assembly

List QR Code

Warehouse

Manager Die Picking

Die Borrowing

Record

Create Die

Assembly List

On-site

Operator

Production

Order

Forging

Production

Requirement

Die

Warehouse

Request for Die

Borrowing and Usage

Scan Die Assembly List QR Code

Create Die

Assembly List

Template

Forging Die

Requirement

Forging Production QR Code Scan to

Turn Off Lighting

and Reset

Figure 1 Work Flow of the Electronic Tag System for the Die Warehouse

56 Forging 2025 CF

Die & Tooling

This integration facilitates seamless information

exchange and enhances operational coordination,

thereby improving the overall level of digitalization

within the factory.

Data Storage

The system records data throughout the picking

process, including picking times, quantities,

anomalies, and other relevant metrics. This data

storage capability supports subsequent data analysis

and effective die inventory management.

Building on the business process and functional

analysis outlined above, the hardware and software

components of the intelligent picking system for

the forging die warehouse can be designed and

developed in detail.

System hardware selection and overall design

Die Racking

The forging die shelves utilize a three-tier structure,

with each tier comprising 16 storage spaces, resulting

in a total of 48 storage positions per shelf. Based on

the actual layout of the factory's die warehouse, a total

of 12 shelves are required. Both the communication

interface module and the electronic tag module are

installed on each die rack.

Electronic Label Module

The system utilizes electronic ink-screen

shelf labels, which are energy-efficient. Each

electronic tag integrates an ink screen, indicator

lights, customizable buttons, and communication

interfaces. The button functions can be tailored to

specific needs, such as confirming picking actions,

issuing out-of-stock reminders, or reporting die

abnormalities. Any button action is subsequently

fed back to the background information system. To

enhance communication reliability in the presence

of signal interference in the workshop, the system

employs wired signal transmission via the CAN

Figure 2 Electronic Tag

High-light indicator

Customization

bus. A total of 576 electronic tags are required, with

each equipped with a QR code area for scanning,

which enables querying of warehouse information,

as illustrated in Figure 2.

After the die management information system

sends the command to sort dies, the indicator light

of the corresponding electronic tag lights up. The

die store administrator picks the dies according to

the number of electronic tags displayed in the store,

and presses the customized button to confirm and

extinguish the high-light indicator after completion.

IoT Controller

The IoT controller is the central device that

establishes the connection between the PC and the

electronic tags on the shelves. It is responsible for

managing communication between these devices

and ensuring the smooth and reliable transmission

of data. Through the IoT controller, users can

remotely monitor and control the devices connected

to the IoT system, enabling remote operation and

management. Additionally, the controller distributes

the processed data to designated terminals and

supports integration with other systems, facilitating

data sharing and application integration. The IoT

controller selected for this system is shown in

Figure 3, with its main parameters listed in Table 1.

Considering the communication rate limitations of

the CAN bus and the relatively small data volume

associated with the storage tags, each IoT controller

is connected to 96 electronic tags, distributed across

two shelves. With a total of 576 electronic tags in

the system, six IoT controllers are required.

2025 CF Forging 57

Die & Tooliing

Interface Parameter

Ethernet Por 2×10/100Mbps Port、1×WAN+1×LAN

Interface CAN×1、RS485×1、Industrial Terminal

Wi-Fi 2.4G

TF Card Supports Mirco SD

USB USB2.0×1

IO Interface 4×DI、4×DO

TABLE 1 IoT Controller Parameters

Figure 3 IoT Controller

IoT Controller 1

IoT Controller 6

……

TCP/IP

Tag

Electronic 576

Tag

Electronic 576

Tag

Electronic j

Tag

Electronic 96

Tag

Electronic i

Tag

Electronic 1

Factory Local Area Network (LAN)

Mold Warehouse Management PC Mold Warehouse Switch

Figure 4 System Hardware Architecture

Overall system hardware architecture design

The tool library management PC communicates

with the MES server over the plant's local area

network (LAN). At the same time, the management

PC interfaces with the IoT controller via a network

switch. The IoT controller in turn connects to

the electronic tags via the CAN bus. The overall

hardware architecture of the system is shown in

Figure 4. All system data is stored in the database

of the MES server, and the forging die storage

management system software runs on the die

storage management terminal.

Die in/out algorithm

Die Out Sorting Algorithm

When the system carries out the die from the

warehouse sorting operation, by scanning the

QR code of the die assembly list, it shows the

shelves where the dies are located and the quantity

information, which facilitates the sorting operation

and accelerates the sorting efficiency. Whether

the electronic tags are all extinguished is used to

determine whether the die sorting operation is over,

ensuring the accuracy of die sorting. The algorithm

flow of the die sorting function is shown in Figure 5.

Die storage operation algorithm

When the dies are loaned and need to be

returned after use, scanning the QR code of the die

assembly list can realize fast and accurate storage

operation. First, inspect the dies before returning

them to the warehouse, scan the QR code of the die

assembly list after passing the inspection, and light

the indicator lights of the corresponding labels

of all the dies in this die assembly list. Then, the

die return to the storage, at the same time by the

electronic tag on the key to confirm the storage.

When all the electronic tags are off, the die return

to storage operation is finished. The algorithm flow

of die return to storage is shown in Figure 6.

System Development and Applications

Based on the above algorithmic process, the

picking system software is developed and integrated

with the forging die warehouse management

information system. First of all, the die warehouse

58 Forging 2025 CF

Die & Tooling

administrator operates the management terminal

PC, queries the number of dies in the warehouse

through the die management software to generate

a list of dies borrowed for loading or a list of dies

to be returned to the warehouse for loading, and

the list of dies contains the information of die

storage positions. Then, the warehouse manager

scans the QR code of the die assembly list, and

the management terminal sends the pending die

information to the IoT controller through the

switch. Then, the IoT controller receives the

information transmitted from the switch, converts

the picking task into the physical coordinate

mapping information of the storage position,

and sends the information to the corresponding

electronic label. The indicator lights on the labels

illuminate, displaying the number of dies picked.

The warehouse manager, guided by the illuminated

positions, then completes the die in/out operation.

Once all the dies in the assembly list have been

Conclusion

(1)According to the forging factory die

warehouse management actual demand, research

and development based on the electronic label die

warehouse intelligent picking system. The system

meets the requirements of high efficiency and

accuracy of sorting operation when forging dies

are out of storage and in storage, and improves the

standardization and informationization level of die

management.

(2)Studied the business process of the die storage

electronic labeling system, and carried out the

system hardware selection and overall architecture

design. The system includes server, management

terminal, switch, IoT controller, electronic label and

other parts. The algorithmic process of die outgoing

and incoming is given, and the developed intelligent

picking system is successfully applied in the die

warehouse of a forging factory.

Start

Receive Production Task

Scan Die Assembly

List QR Code

Electronic Tag Lights Up

Pick According to

Tag Indicator Light

Confirm by Pressing

the Button After Picking

All Tag Indicator Lights

Turn Off

End

Figure 5 Die Borrowing and Sorting

Algorithm Process

Start

Borrow and Return

Inspect Die for

Qualification

Die Maintenance

Scan Die Assembly List

Record Maintenance Reason

Electronic Tag Lights Up Record Maintenance

Personnel

Return and Store in Warehouse

Can It Be Repaired

Confirm by Pressing the Button After Each Location Return

Die Scrapping

Check If All

Electronic Tags Are Turned

Off Record Scrapping Reason

Update Die Assembly

List Status Extract Valid Data

Update Die Inventory and Lifespan

End

Figure 6 Die Return and Storage

Algorithm Process

sorted, the execution

results are sent to the

server via the electronic

tag's confirmation button.

The system software is

developed on the Qt5.15

platform using C/C++

programming languages

a n d e m p l o y s M y S Q L

d a t a b a s e . P r a c t i c a l

applications in a vehicle

parts forging factory's die

warehouse demonstrate

t h a t t h e s y s t e m

significantly enhances the

efficiency of die inventory

management and in/out

operations.

2025 CF Forging 59

Die & Tooliing

Research on Lubrication and Anti-wear

Phosphating Technology for Cold Forging

Lei Lei·Confederation Of Chinese Metalforming Industry

Song Laishuan , Shen Yudong -Shanghai Zhishi New Material Technology Co., Ltd

I

n recent years, with the rise of industries such

as automobiles, new energy, and advanced

equipment, China's forging technology,

especially the more precise cold forging forming

technology, has witnessed rapid development.

Lubrication technology, which plays a crucial

role in the cold forging forming process, has

also received increasing attention and emphasis

from more and more enterprises and scientific

research institutions. Under the current situation,

against the backdrop of the implementation of the

national \"dual - carbon\" policy, enterprises' efforts

to reduce costs and increase efficiency, and the

international economic pattern, the need to develop

and use lubricants with simple processes, superior

performance, environmental friendliness, and low

consumption has become increasingly urgent.

In addition, many cold - forged parts produced

by domestic cold forging forming enterprises, such

as automotive differential bevel gears, bearing

sleeves, motor parts, crankshafts, etc., are subject

to alternating or rotating loads and require good

wear resistance and lubrication performance. This

can be achieved by treating the surface of the

finished workpiece with anti - wear phosphating

(commonly manganese phosphate or zinc - calcium

phosphate phosphating). With the intensification of

competition and continuous industrial upgrading,

effectively improving the anti - wear phosphating

effect through process optimization has also

become a technical topic closely watched by major

enterprises.

Concept of Cold Forging and the

Necessity of Lubrication

The History of Cold Forging

In the 18th century, France used the cold extrusion

method to produce lead bullets. During World War I,

both warring parties adopted the forward extrusion

method to produce brass cartridge cases. The world

recognized industrial cold forging of steel began

in Germany during World War II. After World

War I, the victorious countries embargoed copper

resources against Germany. On the eve of World

War II, the German government included the plan

of producing cartridge cases with steel instead of

copper in the top secret national research projects.

In 1934, steel cartridge cases for bullets and shells

were trial produced by cold forging.

The necessity of cold forging lubrication

In industrial production, cold forging is a type of

metal plastic forming. It uses dies to process metal

blanks below the recrystallization temperature

of the metal (usually at room temperature).

There are internal friction and external friction

in metal plastic forming. Internal friction occurs

at the grain boundaries or slip planes within the

deformed metal, while external friction refers to the

friction generated at the contact surface between

the deformed metal and the tool (Figure 1). The

60 Forging 2025 CF

Die & Tooling

and solids. Enterprises can adopt different types of

lubricants and processes based on the characteristics

of different products and processes. With the

continuous development of lubrication technology

and the upgrading of environmental protection

requirements, oil - based lubrication is rarely

used in cold forging. Currently, in industrial mass

production, the lubrication related to cold forging

mainly adopts the following three types: liquid

emulsions, which are commonly known as polymer

lubricants in the industry; liquid phosphates & solid

organic salts, such as the phosphorus saponification

of iron and aluminum; and molybdenum disulfide.

The specific classification is shown in Table 4.

Phosphorus saponification process

The concept of phosphorus saponification

When cold forging steel parts, the pressure

Figure 1 Forms of External Friction

direction of the external friction force is opposite

to the direction of the movement of the particles,

hindering the flow of metal particles. In most cases,

it is harmful to plastic forming, which is mainly

manifested in the following aspects: changing the

stress within the deformed body and increasing

the deformation resistance; causing non-uniform

deformation, generating additional stress and

residual stress; and reducing the die life.

Therefore, in order to reduce the harm of friction

to plastic forming, lubrication is often adopted,

that is, applying lubricants to the contact surface

between the tool and the deformed metal, which

makes the metal plastic forming technology more

complex. Lubrication is the most effective measure

to reduce the adverse effects of friction on the

plastic forming process. The main functions of

lubrication are as follows: reducing the friction

force between the contact surfaces (the friction

coefficient after phosphating treatment is shown

in Table 1); increasing the die life (reducing wear

and cooling the die); improving the product quality

(reducing the surface roughness and enhancing

the uniformity of the internal structure); reducing

the deformation resistance and forging pressure;

increasing the deformation limit of the material (the

allowable deformation limits of the materials are

shown in Table 2 and Table 3).

Overview of Cold Forging Lubrication

According to the physical state, forging lubricants

can be divided into two major categories: liquids

Table 1 Friction Coefficient after Phosphating Treatment

Table 2 Allowable Deformation

Limits of Carbon Steels and Low

Alloy Steels

Table 3 Allowable Deformation Limits of Non-ferrous

Metals in Cold Extrusion

2025 CF Forging 61

Die & Tooliing

on the contact surface is as high as 2000 - 2500

MPa. Generally, the billets need to be phosphated.

Phosphates are used for steel parts, fluorosilicates

are often used for aluminum parts, and oxalates are

used for stainless steel parts. A fine flake inorganic

phosphate film with a thickness of 10 - 20 μm (5 -

15 g/m2

) is formed by chemical methods. The film

is porous and can adsorb lubricants. Meanwhile, in

the subsequent process, a sodium stearate solution

(2 - 4 g/m2

of surface soluble soap) is commonly

used. When the phosphate film and the stearic

acid solution are heated and soaked, they react

to form a metal soap - zinc stearate (Figure 2).

With the continuous development of technology,

organic resin based lubrication can also be used

after phosphating. In this way, there is no residue

of surface soluble soap on the surface of the

workpiece after lubrication, and the problem of die

accumulation can be greatly improved (Figure 3).

Characteristics of the phosphorus saponification

film as a lubricant carrier: It can withstand the high

pressure of cold forging without being squeezed

away; it can endure a temperature of around

300°C for a short time without being decomposed

or damaged; and it can extend along with the

deformation of the blank without being torn.

Table 4 Categories of Forging Lubricants

62 Forging 2025 CF

Die & Tooling

The technological process of phosphorus

saponification

The standard technological process of phosphorus

saponification: Shot blasting - Degreasing - Water

washing - Water washing - Pickling - Water washing

- Water washing - Neutralization - Phosphating -

Water washing - Saponification - Hot water washing

- Drying

Quality Control in the Production of Phosphorus

Saponification Process: (1) Process Control,

including confirmation of shot blasting status,

concentrations of various tank solutions (FAL/

TA/FA/AC/Fe/saponification concentration),

temperature, time, etc. (2) Result Control: ①

Film weight cwt: Soluble soap layer, metal soap

layer, phosphate layer. The testing methods can

refer to \"Metallic and other inorganic coatings -

Phosphate conversion coatings on metals\" (GB/T

11376 - 2020). ② Visual inspection: Observe the

morphology of phosphate grains in sunlight. The

grains should have a shiny luster like broken glass.

③ Touch feeling: The saponified surface should feel

slippery, and a thin lubricating layer can be scraped

off with a fingernail (Figure 5).

In industrial production, for a fully automatic

phosphorus saponification production line, it is

common to use an overhead gantry crane for vertical

lifting above a track type horizontal linear moving

production line (Figure 6). The production line

mainly consists of tank bodies, guide rail frames,

gantry cranes, drums, working platforms, pipeline

systems, auxiliary loading and unloading systems,

exhaust gas and mist suction systems, electrical

control systems, and liquid - receiving trays at the

bottom of the tanks. The production line is equipped

with a PLC (Programmable Logic Controller),

and the operating status of the production line can

be dynamically displayed through a touch screen

computer. Various process parameters such as time,

temperature, and faults can be shown.

Figure 2 Zinc stearate Figure 3 Organic resin

based lubricants Figure 4 The state of steel after phosphorus

saponification treatment

Figure 5 Lubricating layer on the

saponified surface

Figure 6 Fully Automatic Phosphorus Saponification

Production Line

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Environmental friendly polymer

lubrication process

Background of polymer lubrication process

Since the birth of the cold forging process,

phosphorus saponification has always been the

mainstream lubrication method for cold forging.

Phosphorus saponification has excellent lubricity

and cost advantages, but it also has many problems,

such as high energy consumption and being

environmentally unfriendly. Under the pressure

of domestic environmental protection policies

and forging costs, these problems have become

increasingly prominent. Therefore, for cold forging,

new energy saving and environmentally friendly

lubrication methods have emerged. Shanghai Zhishi

Company took the lead in developing the QT -

CF series of polymer cold forging lubricants in

China. After being coated and dried on the surface

of workpieces, these lubricants have excellent

lubricity, good anti rust performance, and cause

less mold build up. They can partially replace the

traditional phosphate& stearate saponification

lubrication method and are suitable for the

processing lubrication of cold forging and finishing

of bevel gears, synchromesh gears, universal joints,

tripod joints, pistons, cross shafts, bearing brackets,

sleeves, shafts, etc.

Polymer lubrication process

The polymer lubrication process is a liquid type

lubrication method. The lubricant is a mixture

composed of emulsions such as mineral oil,

emulsifier, paraffin, and resin. It is water based and

environmentally friendly. The optimized formula

endows it with excellent cold forging processing

performance. The standard technological process is:

shot blasting & sand blasting — hot water washing

— polymer lubrication — drying — cold extrusion.

When the polymer lubrication process is adopted

in cold forging, it has excellent lubrication and die

cooling functions, which can extend the service

life of the die. At the same time, it significantly

reduces the emissions of waste water and waste

gas, and no phosphating slag is generated. The

problem of lubricant accumulation in the die cavity

has also been greatly improved. In addition, due

to the small footprint of the production line and

high lubrication treatment efficiency, an in - line

process layout (Figure 7) can be achieved, which

also greatly alleviates the problem of a large variety

of in - factory materials in transit in the traditional

phosphorus saponification process.

Figure 7 Cold forging In - line production line

Characteristics of Polymer Lubrication Film

Unlike the chemical reaction type film of

phosphorus saponification, the polymer lubrication

film forms strong adhesion with the metal substrate

through the special formula of the polymer

lubricant. After thorough drying, the film adheres

tightly to the surface of the metal matrix, acting

as a barrier between the tool and the material.

Meanwhile, a lubricating film layer is formed on the

outer surface, enabling cold forging to be realized.

See Figure 8.

Application of Polymer Lubrication Process

In view of the many advantages of the above

mentioned polymer lubrication film, some large

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and medium sized cold forging enterprises in China

adopted this process more than a decade ago, and

the number of enterprises adopting this process has

gradually increased in recent years. Among them,

for finish-forged cold forging parts with a small

amount of deformation, the polymer lubrication

process can completely replace the phosphorus

saponification process, with obvious environmental

and cost advantages. For example, this applies to

the finishing of automotive differential bevel gears,

automotive transmission synchromesh gears, and

automotive constant velocity joints.

The process of phosphating film& polymer film

combines the two advantages of excellent ductility

of the phosphating layer and excellent lubricity of

the polymer, which can greatly extend the service

life of the mold originally using the phosphorus

saponification film process. Shanghai Automotive

Transmission Corporation adopted this process in

the early 1990s. For example, the average service

life of the mold for the stepped shaft of the DCT250

transmission is about 70,000 times. With the gradual

increase of pressure from environmental protection,

comprehensive costs, etc., we have verified through

a large number of practical applications:

(1) Cold extrusion of cup-shaped parts with a

large deformation amount ≤ 70%: The service life

of the molds with polymer film is equivalent to that

of the molds with phosphorus saponification film.

(2) For forward and backward extrusion of

workpieces with small and medium deformation

amounts ≤ 50% and for workpieces with

symmetrical shapes of special-shaped parts: The

service life of the molds using polymer films is

equivalent to that of the molds using phosphorus

saponification films.

(3) Cold sizing: The service life of molds with

polymer film is comparable to that of molds with

phosphorus saponification. During the finishing

process, the polymer film significantly improves the

problem of mold build-up.

(4) For asymmetric special-shaped parts, in the

local areas with a large amount of deformation:

The local parts of the mold using the polymer

film are more prone to wear and galling compared

to those using the phosphorus saponification

film. It is recommended to adopt the phosphorus

saponification process or the process of phosphating

film& polymer film.

In addition, optimizing cold forging die

technology through applications such as coating,

post-nitriding coating, cemented carbide, cemented

carbide & coating, and cemented carbide with low

adhesion to steel (intergranular bonding) can surely

ensure that the overall cost of applying polymer

films is lower than that of traditional phosphorus

saponification.

Control Methods of Polymer Lubrication Process

During the production process, the cumbersome

laboratory tests for multiple indicators in the

phosphorus saponification process are eliminated,

and the process control is simple. In the polymer

lubrication process, firstly, an appropriate shotblasting or sand-blasting process should be selected

according to the product. The particle size of the

steel shots or sand should be properly chosen, and

the appropriate time should be set. Secondly, the

most important aspects are the selection of the

Figure 8 Analysis of Polymer Film and Phosphorus

Saponification Film

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polymer type and the control of the solid content

(concentration). For the determination method of

the solid content of the polymer agent, a moisture

meter is preferably used. Since the operation is

very simple, if a moisture meter is not available,

the traditional drying method can also be used for

determination.

Determination method: ① Set the electric furnace

to 110℃. ② Place the aluminum foil dish on a

balance (accurate to 0.01g or less), weigh it and

record the weight. ③ Use a dropper to take 1g of

lubricant, weigh it and record the weight. After

spreading the lubricant in the aluminum foil dish

thinly, place it in a drying oven at 110℃ for two

hours to evaporate its moisture, and then weigh it

again. The solid content percentage of the lubricant

used = [ (Weight after drying ⑤ - Weight of the

aluminum foil dish ② ) / (Weight before drying ③

Weight of the aluminum foil dish ② ) ] × 100%.

Surface anti-wear (manganese)

phosphating technology

The concept of anti-wear (manganese) phosphating

Anti-wear (manganese) phosphating technology

is a special phosphating treatment technique, mainly

used to form a tough, wear-resistant, anti-abrasive,

corrosion-resistant, non-conductive, highly alkaliresistant, and chemically stable inorganic film layer

on the metal surface. This technology is mainly

applied under heavy-load conditions with high

temperature, high pressure, and chemical reactions,

aiming to improve the corrosion resistance, wear

resistance, anti-slip property, and lubricity of metals.

Through anti-wear (manganese) phosphating, metal

phosphides are formed on the metal surface through

the co-generation of metal phosphating agents and

surface phosphating. Its basic components include

substances such as Mn2

O3

, Fe2

O3

, Mn3

(PO4

)2

, and

Mn3

(PO3

)2

and it appears gray or black.

The application scope of anti-wear (manganese)

phosphating technology is extensive, including

but not limited to fields that require high wear

resistance and corrosion resistance, such as the

manufacturing of heavy-duty mechanical equipment,

precision electronic components, automotive

parts, petrochemical equipment, and hydraulic

components. In addition, this technology can also

be applied to the manufacturing of other items with

requirements such as wear resistance, corrosion

resistance, non-conductivity, and chemical stability,

such as medical devices, solar cells, semiconductor

materials, water treatment equipment, etc. Some

products of cold forging forming enterprises,

such as automotive differential gears, motor parts,

compressor crankshafts, and oil pipe couplings,

which are subject to alternating or rotational loads

and require good wear resistance and lubrication

performance, can be obtained by conducting antiwear (manganese) phosphating treatment on the

workpiece surface.

Standard anti-wear (manganese) phosphating

process: Degreasing — Water washing — Water

washing — Pickling — Water washing — Water

washing — Surface conditioning — Phosphating —

Water washing — Hot water washing — Drying —

(Rust - preventive oil).

Experiment on Exploring Phosphating Effects

under Different Phosphating and Surface

Conditioning Conditions

In actual production, the above mentioned standard

process may not necessarily meet the quality

requirements of all products. Based on years of on-site

debugging experience for customers, different products

need to be adjusted through the overall process

flow and the control of key process parameters. For

example, although the processing time of the surface-

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conditioning process is 10-60 seconds, surfaceconditioning agents with different concentrations

and formulas can play a decisive role in the quality

of the phosphating film. Tests have verified that the

phosphating effect is optimal under the conditions of B

- 3 surface-conditioning and phosphating.

Performance requirements after phosphating

(1) Appearance: Uniform, dense, and black.

(2) Film weight and thickness: Generally, the film

thickness is required to be 3 - 10μm, and the film

weight is 5 - 20g/m2

. The film thickness is detected

by a magnetic film thickness gauge, and the film

weight is detected in accordance with \"Metallic and

other inorganic coatings - Phosphating coatings on

metals\" (GB/T 11376 - 2020).

(3) Surface roughness: In the current automotive

industry, the general requirement is Ra ≤ 1.5μm.

However, some individual OEMs have particularly

stringent requirements, demanding Ra ≤ 0.8μm.

This requires enterprises to have a high level of

control in both the machining of the base material

and the phosphating process during the production

of manganese phosphated parts in order to produce

qualified products.

(4) Microscopic SEM structure: Generally

tested by a scanning electron microscope. The

requirements are that the particle size should be

less than 10μm, with a dense crystal structure. The

high temperature manganese phosphate film shows

polyhedral block shaped crystals. The smaller the

size, the better. The arrangement should be uniform,

and the lower the porosity, the better.

(5) Requirements for phosphating film pits:

Pickling pits should be less than 30μm.

(6) Coefficient of friction: The coefficient of

friction refers to the ratio of the frictional force

between two surfaces to the vertical force acting on

one of the surfaces. This is required for oil - coated

manganese phosphated petroleum pipe couplings and

high strength bolts. Generally, for ordinary threads,

it is required to be 0.09 - 0.14, and for high - strength

threads, it is 0.12 - 0.18. Detection can be carried out

using appropriate instruments in accordance with the

national standard GB/T 3098.1 - 2010.

Post manganese phosphating process

After manganese phosphating, a void reticular

structure is formed on the surface of the workpiece,

which can absorb more lubricating and rust proof

media such as rust proof oil, effectively improving

anti-wear and lubrication performance. Therefore,

in industrial production, post treatment is generally

carried out after manganese phosphating. The

most commonly used methods are as follows: (1)

Applying rust proof oil is the best way to improve

the corrosion resistance of the film layer. Rust proof

oil can be evenly applied to the surface by dipping

or spraying. After application, the neutral salt spray

test of the workpiece can reach 48 - 96 hours, which

is sufficient to meet the use of parts in most working

conditions. (2) Spraying molybdenum disulfide.

Molybdenum disulfide is an excellent lubricant with

high temperature resistance. It is often used on parts

with special anti-wear and lubrication requirements

in automotive engine components and the aerospace

field. The friction coefficient of the molybdenum

disulfide lubricating film is 0.02 - 0.09. The friction

between the two metal surfaces is converted into the

slip between the layered structures of molybdenum

disulfide, thus reducing friction and wear.

Phosphorus Saponification/Anti-wear

(Manganese) Phosphating Wastewater

and Solid Waste Solutions

Wastewater Treatment Plan for Phosphorus

Saponification/Anti-wear (Manganese) Phosphating

Wastewater and waste gas from phosphorus

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saponification/anti-wear (manganese) phosphating

must be effectively treated and can only be

discharged after meeting the standards. The main

sources of wastewater are the rinsing water after

degreasing, pickling, and phosphating, as well as

the regular replacement and discharge of degreasing

and phosphating solutions. The main pollutant

components in the wastewater include COD,

ammonia nitrogen, TP, zinc, nickel, etc. A relatively

mature wastewater treatment plan is shown in

Figure 9.

Treatment Plan for Saponification Waste Liquid

(1) The main chemical components of the

saponifying agent are a mixture of sodium stearate

(C17H35COONa) and glycerol. It is a white oily

powder with a slippery feel and a fatty odor. When

used in the workshop, it is mixed with water

at a ratio of 5% - 7% to form a saponification

solution. After a period of use, with the continuous

introduction of the phosphating solution, when

the zinc ions, phosphate ions, iron ions, and free

acid in the saponification solution reach a certain

concentration, the saponification effect will decline,

which is regarded as an aging phenomenon, and

the solution needs to be updated or re-configured.

Normal saponification solution indicators: FAL is

(-0.5) - 1.0 pt, B.N.O. is 1.5 - 2.5 g/L, Zn < 500 mg/

L, Fe < 500 mg/L, PO4

< 2.5 g/L.

(2) Treatment methods.

① The chemicals used include sodium stearate

based lubricant products, saponification waste liquid

separator QT-SWT335, and inorganic acids such as

hydrochloric acid/sulfuric acid.

② Treatment method: Add 10 kg (1%) of the

saponification waste liquid separator QT - SWT335

to a 3% - 5% lubricant solution (1000 L), then add

fresh acid to adjust the pH to 3 - 4. At this time, the

consumption of fresh acid is approximately 10 - 15

L. After stirring and cooling to room temperature,

skim off the floating matter. For the remaining waste

liquid at the bottom, add an alkaline solution for

neutralization until the pH value reaches 6 - 7, and

then it can be discharged into the sewage treatment

system for self-treatment.

Figure 9 Treatment Plan for Phosphating Wastewater and Exhaust Gas

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Waste acid can also be used to treat lubricating

waste liquid. However, due to its low concentration

and high iron content, the consumption of waste

acid is relatively larger, which is 2 to 4 times that of

fresh acid. It is recommended to use fresh acid for

treatment.

(3) Practical cases are shown in Figure 10 and

Figure 11. Improvement effects: By introducing

this process, the enterprise reduces the discharge

of waste saponification liquid by 1.1 tons per

week, with a reduction rate of 88%. The treatment

cost is decreased. Moreover, the on site working

environment is effectively improved, and the labor

intensity of workers in bagging is reduced. The

overall effect is quite good.

Future Technological Prospects of Cold

Forging Phosphating

Online shot blasting technology

At present, due to cost saving considerations

or backward ideology, many enterprises have

numerous problems such as mixed use of shot

blasting machines and failure to replace steel shots

regularly. In fact, these issues have a significant

negative impact on the cold forging effect of

products and the service life of molds. Online

shot blasting, wet shot blasting, and dedicated use

of shot blasting machines should be among the

technological optimization directions that cold

forging enterprises should focus on in the future.

Acid washing alternative technology

At present, in the phosphorus saponification and

anti - wear (manganese) phosphating processes,

HCl or H2

SO4

is commonly used as the pickling

medium, which is irreplaceable. However, problems

such as acid mist volatilization, poor working

environment, and environmental protection issues

often cause headaches for enterprise managers. The

Figure 10 Application Case I

Figure 11 Application Case II

development of an effective pickling alternative

process or related chemical media is of great

significance and application prospects.

Technology for the Reuse of Phosphating Slag

The phosphating film formed in phosphorus

saponification is thick, and the temperature in anti

- wear (manganese) phosphating is relatively high.

The direct result is that relatively more phosphating

slag is produced during the phosphating process,

about 3g/m2

. At present, most domestic enterprises

basically treat it as solid waste directly, which is

costly and not environmentally friendly. There are

cases abroad where the phosphating slag is recycled

and processed into building materials. In the next

step, we will also research and develop more

environmentally friendly technologies for the reuse

of phosphating slag.