Even tooling needs a home.

Definition of a Die Set

A die set can be defined as a sub press unit consisting of a lower shoe and an upper shoe together with the guidepost and bushing, by means of which the shoes are aligned. 

The punches and die components are mounted on the inner surfaces of a die set this completes a finished punch press tool.

Purpose of a Die Set

1. Accuracy of set up: Because the die components are all mounted together in the die set it creates a single unit making it easier for accurate setup.
2. Improve piece part quality: This is because of the accurate setup.
3. Increases die life: Because the die set allows for proper alignment.
4. Minimum set up time: Being a single unit, the die set with the components accurately set up, greatly reduces set up time in the press.
5. Facilitates maintenance: Allowing different components to be serviced or removed without affecting other components.
6. Alignment of punches and die members: Facilitates a means to keep the die safely together.
7. Ease of storage: Again being a single piece it makes it easier to handle a die.

Terminology Pertinent to Die Sets

Die shoe: The die set base is called the die shoe.

Punch holder: The die set top member is called the punch holder.

Shank: Most punch holders in the smaller sizes are made with a shank which fits the clamping hole in the lower end of the punch press ram.

Guide Post: Guideposts are cylindrical pins which provide a means of alignment for a die set.

Guidepost Bushing: Bushings are installed in the opposing shoe and engage the guide post with a close sliding fit.

Flange: This is a ledge that extends beyond the die areas to provide a means for clamping the shoe members to the bolster plate or press ram.

Die Area: Areas on the top and bottom of the die for mounting the die and components.

Shut height of the die: this is the distance from the bottom of the die shoe to the top of the punch holder when the die is in its closed position.

Materials for Die Sets

1. Gray iron or cast iron containing 10 to 25 percent steel.

2. Hot rolled boilerplate -1018 to 1026 SAE.

3. A combination of platens or a casting and some other steel.

4. Aluminum magnesium as well as soft semi-hard or hardened tool steel. 

Die Sets: Types and Styles

Die sets are rarely custom built. One of the advantages is that they are readily available straight out of a catalogue. These die sets are commercially produced in a variety of configurations:

1. Back post 2. Corner set posts

3. Diagonal post 4. Four posts one in each corner

Types and Styles of Guideposts

Die sets come not only with different styles of post arrangement, but they also can have a variety of guidepost arrangements:

1. Commercial guidepost: There is the centerless guidepost that is the same diameter throughout.
2. Precision guidepost: These guideposts are press-fit into the die shoe. The difference between the two is simply a precision grade. The precision post is normally chrome and lapped or honed.
3. Shouldered Guidepost: These have a large press-fit shoulder into the shoe.
4. Self-aligning Guidepost: These were developed in order to eliminate jamming of the pins in the guide bushings.
5. Removable Guidepost: These are for ease of access and facilitate in accessing certain components.

Bushings, which also play a very important role in maintaining the accuracy of a die, can come in a number of variations. They are normally broken into several categories from precision bushings, bronze bushings, commercial bushings and finally, bushings for shoulder guideposts.

Tolerances on Die Sets

Die sets normally come in 3 tolerances: 

1. Super-precision sets 0.0002 of an inch total clearance is a CLASS 1 fit.
2. Precision sets 0.0003 to 0.0005 of an inch total clearance is a CLASS 2 fit.
3. Commercial sets 0.0006 to 0.0009 of an inch total clearance is a CLASS 3 fit.

Die Set Selection and Ordering

The textbooks have suggested a checklist to use when ordering a die set:

1. Layout the die: Allow sufficient room for all die components.
2. Determine what type of set is needed: Two pins, four pins, rear pin.
3. Select the die area that best suits the configuration in step 1.
4. Select material for die set. 
5. Select the appropriate punch holders and punches that will work with the shut height available.
6. Determine the length of guide pins required based on press shut height.
7. Determine the type of bushing you want on the die set.
8. Select the shank diameter that will fit the press when the die will run.
9. Choose the grade of precision required.
10. Order the set which most closely fits the criteria that we just went through.

The order criteria normally require:

• a catalogue number
• precision or commercial grade
• length of the guide pin
• a type of bushing
• the diameter of the shank
• how to ship

Die Set Lubrication

Die sets, in spite of being a pretty simple component, do require lubrication in order to meet their expected production life. Make sure to consider all the possible lubrication options, in order to reduce wear on the guide pins. Die sets need to have grease nipples in the guide bushing or grease grooves. Some die sets use specially fitted caps with felt washers that are soaked in oil. Proper lubrication is very important to the life of the die set.

Maintenance Procedures

Die sets do require some maintenance, normally only when the die is being serviced, unless it is a highly precise die set that would be used in the electronic industry of the watchmaking industry.

The procedure would be as follows:

1. There is no inspection of the die set during the run unless there is a problem.
2. When the die is taken out of production for maintenance, that is when the die set is visually inspected for any score marks or pickups on the guide pins and bushings.
3. During any other regrinding of the die, the die set shouldn’t require further maintenance.

Conclusion

As you can see a die set saves a lot of time in set up they help maintain accuracy and require very little maintenance. Like most of the other articles in the die building process, this is a summary of the text that I am using to prepare for my C of Q test for my apprenticeship.  If you like what you’re reading, please share and if you want more of it subscribe to our email list and you will be notified as more content comes out.