Metal Stamping

Sheet metal stamping is the process of forming or cutting sheet metal stock in a press tool into a usable part. Generally the material is fed through the tool and the press provides the tonnage for the tool to do work on the metal. The list of processes for metal stamping is long, but a highlight of a few of them we excel at include the following:

• Piercing: This process is a blanket term that describes the cutting and removal of material via a shearing action. Much like scissors, a punch will push material into a hole (called a die) and will break the material along the edge removing it from the sheet or strip.
• Blanking:  Much like piercing, blanking utilizes a punch and die to generate a specific shaped component. The difference in this case is rather than removing a slug as scrap, the piece that falls out will be the actual part.
• Coining: A form of precision stamping where sufficient pressure is used to permanently indent or mark the part. This can be done as an economical replacement to engraving or to put useful features like radii into an edge of a part.
• Embossing:  The opposite to coining, this process uses extreme pressure to create raised features in a part. Examples include embossing ribs for strength or dimples to help locate mating parts.
• Drawing: Similar to embossing but taken a step further, drawing uses high pressure to stretch material into various shapes like cups or cans. This is usually done slowly in multiple steps to avoid ripping or breaking.
• Forming: This process is a blanket term for manufacturing sheet metal parts that includes bending or reshaping material. This is done via plastic deformation and no material is added or removed.

Metal stamping operations will vary depending on the customer specifications but four common ways to manufacture stamped parts include:

• Progressive Die Stamping: This method of tooling is termed progressive because of the way the material “progresses” through the die where each station performs an operation on the strip to produce a final part. The various stations will pierce, blank, form, etc. until the final part is made and cut off from the rest of the strip.
• Transfer Die Stamping: Also known as short-run tooling, transfer die stamping takes the same metal stamping operations found in progressive die tools and breaks them out into individual tools. Operators then manually transfer each part from one tool or station to the next. The advantage here is that the part is not connected to a strip of material. Therefore it can be rotated around freely between each operation.
• Deep Draw Stamping: Deep drawing dies are a special class of tool that are made specifically to stretch and draw material into tall shapes. The stretching and drawing of material causes immense stress and must be done with care over several operations to prevent cracking.
• Multi-slide Stamping: Also called four slide stamping, manufacturers use this versatile technique for elaborate shapes that require numerous or continuous bends to form the workpiece. This process can create bends and coils that are otherwise impossible to make in regular punch press tools even with sophisticated cam and spring systems.

Compared to 3D printing or CNC machining, metal stamping is a much faster and more reliable method of manufacturing metal parts. Automated progressive dies can make parts at a rate of more than 1000 pieces per hour and can hold tolerances of up to +/- .001. Additionally, many stamping tools can be run without an operator present, saving time and money.

Blanking and piercing are very common stamping methods used to create the initial geometry that will become the finalized part. These operations act the same but do have different functions that will affect the overall end result.

Blanking:

Blanking is the process of cutting the exterior edges of the part out of the sheet metal stock. Depending on if the slug is the actual blank or scrap will change where the punch and die clearances are applied. By manipulating the orientation of the blank in the strip we can significantly reduce the amount of scrap, passing the savings to our customers.

Piercing:

Piercing is the process of cutting interior shapes inside the blank via a shearing action between the punch and die. It is similar to blanking but in this case, the slug is always scrap. This means our punches will always be to size and the clearances will be applied to the die. We can cut any shape necessary for our clients, even zero radius corners.

Both piercing and blanking operations are versatile and extremely precise techniques for removing and reshaping sheet metal into a final product. Some of the benefits of blanking and piercing offer include:

• Extremely accurate hole placement and sizing (within +/-.001 or less)
• Cutting of holes in a wide variety of shapes and sizes including corners of .005 or less
• Clean cuts with no need for deburring operations
• Incredibly fast and efficient material removal
• Minimal distortion to part

Coining:

Coining is a form of precision stamping where a punch is used to apply sufficient pressure to the material to permanently indent or mark a part changing its thickness in the affected area. This can be done as a replacement to engraving or etching and can also be used to put useful features like radii into an edge of a part.

At Verdugo Tool & Engineering we use custom punches to coin logos and images into parts to make jewelry as well as coin serial and part numbers for our clients. Additionally we have coined a wide variety of shapes into customer parts including radii, flats, and star shapes all while maintaining a high degree of accuracy.

Embossing:

Contrary to coining where the punch is pressed in and the material is indented, embossing is performed with a punch and die to create a sunken or raised feature where both sides of the material are offset. In an embossing operation the thickness of the material is not affected.

Embossed components can serve functional or aesthetic purposes. Functional applications improve the performance of the part like improving stiffness, providing a mating surface, or marking weld points, etc. Additionally, logos or messages can be embossed into a part for marketing or aesthetic purposes. At Verdugo Tool & Engineering we have embossed boxes, dimples, arrows, and logos for our customers.

Coining and embossing have their own unique advantages compared to other similar manufacturing processes. Below are the individual benefits of each process:

Coining:

• Cheaper and faster than engraving or etching
• High repeatability and accuracy
• Thins and work hardens the material

Embossing:

• Produces a 3D design with visual and tactile depth
• Strengthens and hardens the material
• Cheap and easy to make

Metal forming is a broad category of sheet metal stamping composed of different metalworking techniques used to transform sheet metal into usable parts. Drawing or deep drawing is one type of generic metal forming where manufacturers use carefully crafted punches and dies to stretch the material into various shapes and sizes. Traditionally drawing is used to create cylindrical components but it can be used to form boxes or other irregular shapes as well. Generally speaking the main differences between drawing and forming are as follows:

• Forming generally uses only one hit to to make an embossed or formed shaped while drawing or deep drawing generally uses several intermediary shapes to massage the metal into the final configuration
• Drawing or deep drawing generally uses a spring or air cushion pressure pad to maintain pressure on the part throughout the whole drawing process. This allows the part to remain smooth and stops it from wrinkling
• Both are incredibly accurate and repeatable processes that allow for an endless number of features in a part.

Metal forming and deep drawing are used for a wide variety of different parts depending on customer needs and demands. These are found in all kinds of industries such as aerospace, defense, and automotive. The most common types of parts we work on that use drawing processes are:

• Deep cups with or without coined bottoms and with or without flanges
• Deep boxes with cut out holes and slots
• Toppers with punched holes and shear forms
• Guitar pickup covers with threaded ears
• Many more