Die manufacturing can be a complicated and expensive process. The following information created by our industry experts at The Phoenix Group will help give some insight into the manufacturing process, the required equipment, and basic die anatomy.
WHAT IS A DIE IN MANUFACTURING?
A stamping die is a precision tool that cuts and forms metals into functional shapes. The two die halves are placed inside a press that can generate enough force to perform the necessary die functions. A die can perform four essential functions: locating, clamping, working, and releasing. Out of these four, value-added operations only occur during the working function of the die. This work includes but is not limited to cutting, bending, piercing, embossing, forming, drawing, stretching, coining, and extruding.
WHAT ARE THE COMPONENTS OF A DIE?
Upper and Lower Shoes
Upper and lower shoes are the base where all other die components are attached, and they are typically made of cast iron or steel. Die shoes must resist deflection during the operation of the tool.
Guide Pins and Bushings
Guide pins and bushings are critical components that maintain the locating ability of a die. Guide pins are typically made from hardened steel and attached to one of the die shoes, entering the bushings found on the opposite shoe to locate the two die halves. Bushings tend to be made from a softer material, impregnated bronze, to promote wear on the bushing instead of the pin.
Punches are the male features that work with a die steel to impart the value-added shape to the material. Punches can be used as forming or cutting tools, depending on their needed application. Forming and cutting punches are made of tool steel to combat the high wear the details endure.
Die Steels and Cavities
Die steels and cavities are the opposite, or female, shape of punches; these details also help shape the material. For forming tools, they essentially mirror the punch plus material thickness. The shape is also mirrored for cutting steels but is offset larger to accommodate punch-die breakage. This offset allows proper cutting clearances and the cut material to fall through the tool.
This component’s primary function is to pull or strip the material off the punches after the press has cycled to the bottom. Usually driven by springs, but sometimes solid, the stripper springs are compressed during the downstroke of the press. During the upstroke, the springs return to their original length, pushing the stripper pad and the material off the working punches.
Aligned with die webbing and parallels, these details help prevent catastrophic damage to the tool during a crash event. It is also common to have a slot ground at the top of the block that is used for die set-up.
Pilots and Gauges
Pilots and gauges help locate the strip or a blank before cutting and forming occur.
Nitrogen, coil, or neoprene springs are used to apply holding pressure to the part, strip the part off the tooling, or return details to a home position.
WHAT ARE THE DIFFERENT TYPES OF DIES?
Progressive dies contain multiple operations, forming and cutting on one die shoe. For example, a simple progressive die may look like this:
- Station One – Pierce Operation
- Station Two – Draw Operation
- Station Three – Idle
- Station Four – Flange Operation
- Station Five – Cut-Off
The gap between each station or the material’s progression is a specified distance, called the pitch. The part stays attached to the coil through a carrier strip until it is cut off at or near the final station.
Progressive dies tend to be able to run faster than their larger transfer die counterparts. Progressive dies are also simpler to set up as all stations are attached to a single die set. In addition, material progression is controlled by a coil feed system, eliminating the need for complex transfer systems. Progressive dies typically produce smaller, less complex parts.
Transfer dies contain one operation per die set. The material is then transferred to the next die for a subsequent operation. Each die set performs a specific operation. A typical progression would look like this:
- Operation One – Blank Die
- Operation Two – Draw Die
- Operation Three – Pierce and Trim Die
- Operation Four – Flange Die
The material is separated from the coil in the first die, so other transfer equipment must be used to move the part from die to die. Due to the large part sizes that transfer dies produce, many transfer lines require multiple presses to produce a part.
Transfer dies are capable of handling larger and more complex parts than progressive dies. The downside is that expensive and complicated transfer equipment is needed to move the material throughout the progression. In addition, since each station is its own die, a higher investment is required to manufacture a transfer die line when compared to a progressive die.
DIE BUILDING MATERIALS
- Computer Numerical Control (CNC) Milling Machine
- CNC Wire Electrical Discharge Machine (wEDM)
- Surface Grinder
- Drill Press
- Conventional/Sinker EDM
- Coordinate Measuring Machine (CMM)
- Computer-Aided Design (CAD) Software
- Computer Aided Manufacturing (CAM) Software
- Jig Grinder
DIE MAKING PROCESS
- The die-making process starts with design. First, the part is designed to the customer’s specifications, and then the die is designed to produce that part. Since this design begins the flow of manufacturing, it is critical that as many problems, and potential problems, as possible are caught in this stage. If not, all proceeding activities will likely suffer.
- Next, manufacturing the tool can begin. Material type is selected based on the die requirements. These requirements may include part material, part shape, calculated tonnage, and annual output. Steel is overwhelmingly the most common material used, but the die materials can range from carbide to wood. For most applications, the material must be square for accurate machining. Squared material can usually be ordered from the supplier or milled square on a CNC.
- When the material is on the CNC, details (die components) can be machined to finish dimensions or have extra stock left for a later grind, hard-milling, or wire EDM process. Threads and screw holes are usually finished during this process, while dowels are typically left small to allow for a more precise finishing step.
- Next, the necessary working details will be heat treated. When details are expected to be coated before they reach the final customer, the heat-treat vendor must use a process compatible with the future coating. Otherwise, the needed material characteristics may not be achieved.
- Once the material is heat-treated, finish machining can begin. Several finish machining methods can be used depending on required tolerances, surface finishes, and shop capacity. These methods include wire EDM, jig grinding, polishing, surface grinding, and hard milling.
- When machining is complete, the die can be assembled, dry run (cycled with a crane or hydraulics to verify no dangerous interferences), and placed in a press for tryout. Tryout aims to test the tool for part accuracy, consistency, and production capability.
NEED HELP WITH A DIE MANUFACTURING PROJECT? THE PHOENIX GROUP HAS YOU COVERED!
The Phoenix Group has worked with tool shops, production facilities, and material producers worldwide. Leveraging this experience, we can help manufacturers design and build robust tooling to keep pace with production requirements and part quality. The Phoenix Group can find long-lasting solutions to various manufacturing challenges from tooling buy-offs, formability analysis, problem-solving, and die skills training.
Contact us today at +1 (248) 303-2455 or request a consultation online.