This paper on Die (Manufacturing) consists of an overview of the basic die. how it makes, types of dies, and die materials. Also, you can download the PDF version of this paper for free, the link is at the bottom of this article.
What is a Die?
Die is a kind of solid or hollow metal of customized shape that is mainly used in stamping or cutting any shapes or coin, embossing, drawing wires, extruding, press, etc.
It is a thing that can be customized according to the requirement or necessity. Along with that, anything from simple to complex shapes can be made through a die.
The dies can be used in the formation process or casting process and can be termed as Mould. Die is mainly used in the manufacturing departments of industries. The sections of the die, which are made for forming or cutting, can be made of special metal and hardenable steel and it is also known as Tool steel.
Components of a Die:
Stamping dies have several components. They are as follows:
1. Die Sets, Die Plates and Shoes:
Die Plates, Die Sets and Shoes are made of either aluminum plates or steel plates. In a critical tolerance, these parts are flat or parallel. So they can be grounded or machined-milled. From these all, the popular one is grinding. So that as ground surface, the milled surface also should be accurate.
The die set can be created by attaching lower die shoes and upper die shoes by guide pins. The lower shoe of die contains holes, that are made by flame-cut. These holes help to create scrap and slugs as the die can freely fall on the press. These holes also help as in the clearance of other components as gas springs.
2. Bushings and Guide Pins:
Guide pins are used as guideposts. Guide bushings are used with guide pin to align lower and upper shoes together. Guide pins and guide bushings are the components of precision-ground.
They are made of 0.0001 in. To install the components in the method of numerous specialty, mounting can be used. Two types of bushings and guide pins are present.
They are Ball bearing-style pins and friction pins. Guide bushings are slightly bigger in inside diameter than the pins as they are precision-ground pins. Bushings are made of a special wear-resistant material known as aluminum-bronze and the guide pins are made of hardenable steel. As the aluminum-bronze contains graphite, so it reduces friction.
3. Heel Plates and Heel Blocks:
A special kind of steel block is a heal block. Heal block is screwed, precision-machined, welded and dowelled to lower and upper shoes. At the time of forming process and cutting, side thrust generates.
This thrust is then absorbed by the wear plates and the functional components. The one-directional force may deflect the pins, which can be the cause of misalignment at forming or cutting. So it is necessary to observe that any one-directional force occurred or not.
Heel blocks are mostly made of steel heel plates. In the opposite shoe, there is a wear plate that is made of some dissimilar metals like aluminum-bronze. Heat, cold welding or galling occurs because of the friction made by the same metal in two opposite plates.
As in all directions, the die has a heel, box heel blocks are to be used. In another hand, to heel any or all directions, heel blocks are used.
4. Screws, Keys, and Dowels:
Screws secure and fasten the components which are working in both lower and upper shoes. In stamping dies the fastener is the cap screw socket head.
In Milled pockets of die shoes, the key, rectangular, small block, can be inserted. Keys heel and locate the components and the sections of die.
Dowels are used to locate the proper location of the die section and die shoes. Dowels are usually precision-ground, hardened pins.
At the time of forming and cutting process the pads, flat, pressure loaded plates, used to control and hold the metals.
According to the functions, pads are made from either hardenable tool steel or soft low-carbon steel. At the mating section of the die, it must be closely fit with contoured pads. In stamping dies, there are different types of pads. They are as follows:
a. Stripper Pads:
At the cutting punches, a stripper pad is used to strip or pull the metals. Stripper pads are usually spring-loaded and flat. When it cut, the metal used to collapse on the shank or body. The stripper pads used to mount the die shoes, mainly the upper shoe.
b. Pressure Pads:
Before the contact of forming punch with the metal, in the lower section of die, metal has to be taken down. It is done at the time of the wipe bending process. The amount of bending force and the force pressure pad should be equivalent.
c. Draw Pads:
On the sheets of metals, the amount of downward force and pressure is exerted. This determines that how much flow in the metal can be agreed and the die cavity by drawing can enter. According to that, flow in metals can be controlled by the draw pads.
6. Spools, Keepers and Shoulder Bolts:
The shoes die used to move from up to down. The Spools, Keepers and Shoulder Bolts are used as the fasteners of this movement. By screw or dowels, Spools, Keepers and Shoulder Bolts are secured with lower and upper die shoes.
The retainer can be used to secure the components with lower and upper die shoes at the time of forming and cutting process. The popular retainer among all is a ball-lock retainer. It is a high-precision retainer. It is used to align and secure the forming and cutting punches accurately.
It uses a spring-loaded ball-bearing. In the teardrop shape, the spring-loaded ball-bearings are locked not to come out the punches. This ball-lock retainer gives advantages to the technicians to reinstall the punches by removing it quickly. It is a ball-lock retainer’s advantage.
Spring is a component that can be used to supply force to the strip, form metal and hold it. Different springs can be used here. Most popular springs are gas spring, coil and urethane springs.
Gas springs are filled by nitrogen. It helps by giving a good amount of force. Coil spring is used, when there is a need for the force of a reasonable amount. Urethane spring is worked at short-run stamping. These Coil and Urethane springs are also known as Marshmallow spring.
Types of a Die:
According to the use in the operation of sheet metal, die are of six types. These are:
- Simple Die
- Combination Die
- Compound Die
- Progressive Die
- Transfer Die
- Multiple Die
The simple die is that die where at one stage, one operation can be done by one stroke.
Advantages of Simple Die:
Here are some advantages of a simple die:
- It is the simplest form of the die.
- It is one stroked die.
The Combination die is that die where at one stage, multiple forming and cutting operation can be done by one stroke. Such examples of combination die are as follows:
- Combined deep drawing and blanking
- Combined deep drawing and punching
- Combined bending and blanking
Advantages of Combination Die:
These are some advantages of using a combination die:
- Productivity is too high as the operation is done as a combination of forming and cutting.
The compound die is that die where at a stage, multiple operations can be done by one stroke.
Advantages of Compound Die:
There are couple of advantages of using compound die, and some of those are:
- Multiple components are produced in one stroke.
- Productivity is high.
Limitations of Compound Die:
Here are some limitations of compound die:
- The required force is high.
- No usability of punch forces reducing methods.
- Difficult manufacturing and design of the combination of die and punch, for greater than 3 operations.
Multiple operations of cutting can be performed in a stroke. But blanking is the last operation as different punch sheets and stages are progressing to complete the operation of punching from one to another stage.
Advantage Progressive Die:
Here are the list of advantages using Progressive die:
- By one stroke, multiple components can be produced.
- Productivity is the same as the compound die.
- Force is reduced by providing staggering or shear.
- Manufacturing and design of the combination of die and punch are easier.
Disadvantages of Progressive Die:
Here are some disadvantages of progressive die:
- Force balancing is difficult.
- Precision alignment and setup procedure is required.
- Much heavier than single die.
Transfer die is that die which is the same as the progressive die. With that here, the first operation is the blanking. So that as a first stage, black procedure travels one to another stage and completes the punching.
Advantages of Transfer Die :
These are some advantages of using a transfer die:
- More economical production than progressive die.
- Large parts are transferred in more than one presses.
- More versatile.
Disadvantages of Transfer Die :
Although there are some disadvantages of Transfer die:
- More costly.
- In each stage, has to set the blank.
- More sensor for protection of die is necessary.
More dies attached parallelly to produce more components are known as Multiple Die.
Advantages of Multiple Die:
These are the some advantages of using multiple die:
- Productivity is High.
- In the existence of more than one dies, more products can be produced.
- It consumes less time.
Materials of Die:
To make a die, so many materials are needed to be present. These contain so many steels of different kinds and the material of non-metallic and the casting of non-ferrous and ferrous.
Manganese 0.20 to 0.45, Carbon 0.90 to 1.15, Sulphur 0.025, Phosphorus 0.025 and Silicon 0.16 are present in this Carbon steel.
Carbon Block Steel:
Carbon Block Steel contains manganese 0.50 to 0.70, carbon 0.55 to 0.65, chromium 0.60 to 1.10 and nickel 1.25 to 1.75.
Tungsten Oil Hardening Steel:
This Tungsten Oil Hardening Steel contains manganese 0.25, tungsten 1.75 and carbon 1.20.
High-Alloy Oil-Hardening Steel:
This High-Alloy Oil-Hardening Steel is the non-deforming in nature. It contains about chromium 12.00, carbons 2.15 and manganese 0.35. Other elements, Tungsten, Nickel, and Vanadium can add to this steel.
Manganese Air Hardening Steel:
This Manganese Air Hardening Steel contains manganese 2.5, carbon 0.90, molybdenum 1.00, chromium 1.5 and silicon 0.30.
Chromium Air Hardening Steel:
This Chromium Air Hardening Steel contains chromium 5.00, carbon 1.00, manganese 0.50, molybdenum 1.00, silicon 0.25, and sometimes vanadium 0.50 can be added.
High Alloy Air-Hardening Steels:
This High Alloy Air-Hardening steel is as same as the High-Alloy Oil-Hardening Steel. It contains chromium 12.00. The carbon varies between 1.00 to 2.15, molybdenum 0.80, silicon 0.35, manganese 0.35 and sometimes vanadium 0.50 can be added too.
Materials for Producing Low-Cost Die:
In the aircraft manufacturing process as well as in some other cases a die needs to be developed by a die maker through different materials that can be a better choice rather than using some cast steels or steels.
Although, a die maker needs enormous practice and skill to do the same thing. This type of scenario occurs during the die making that related to aircraft manufacturing to reduce the material utilization cost.
Apart from that, it is also true that the quality of metal that is produced through magnesium or aluminum may not be up to the mark as compared to the quality of cast steel or steel.
Generally, the materials taken into account by a die maker to make a die are Cerrobend, Kirksite, which are non-ferrous material in nature. On the other hand, non-metallic materials such as bakelite, plastics, Masonite and different kind of woods are also can be utilized to make a die. Moreover, these materials are going through the stretch forming process to make a die.
Die Making Process:
First of all, the die shop within a mechanical workshop has to ensure that every die maker should be properly trained as well as aware of the fact through which a die can be developed. In this era of modernization, in most cases, every die maker creates a design in AutoCad and tests that through a prototype tool. Apart from that, the processes that should be incorporated with the die making process are discussed below briefly.
The die maker imports the design from the database and checks the precision of the drawing. In the next step, the die maker counts the time through a blank design and determines the phases of completion. Such as the width of a strip distance between pitch, angle and so on.
Now it becomes a fact that most of the companies compare the drawing with a standard drawing through the visualization process. The next step is developing the shapes according to the requirements.
In regards to this finite element analysis, that should be carried out by the die maker to analyze the draft angles, safety zones as well as the other calculations. In the other step, errors are encountered by the die maker. Henceforth, the layout is made and developed a free form shape.
ECO or Engineering Change Order can be utilized to design the tool. After that, a template should be created according to the standard deviation. Then in the next step, the die maker deals with the making process of the prototype tool. In this case, Cimatron's NC is used regarding the same. Through this NC, set up of a high-quality die can be developed and its precision can be secured appropriately by the die maker.
So this is a complete paper on Die, I hope you have understood the key factors regarding dies. If you have doubts, feel free to share it in the comment section, we will love to help you back. And in the meantime don not forget to share this resource in your favorite social media handles.
References (External Links):
- Die Making - Inno-PROdukt Kft
- Manufacture high quality complex molds and dies | Autodesk
- Manufacturing of Dies and Molds - ScienceDirect
- All the images used in this paper are made by Learn Mechanical under Creative Common License [Attribution Needed].