Metal stamping, or metal pressing, is a manufacturing process dating back to blacksmith days. Stamp press technology has developed throughout history to create the modern punch press machine. This metalworking tool is used to shape or cut sheet metal to precise specifications, producing large volumes of metal pieces at a low cost.
This is generally done using standard or custom-designed dies, one on the base plate and one attached to the ram, which is driven down to shape the metal placed between. There are many different techniques in punch pressing to create required shapes and finishes. This versatility is what makes stamp presses so instrumental in the automotive, aerospace, and electronics industries.
To help you understand what stamp presses can do and the end result, we’ve compiled this simple guide with an overview of all the basics you need to know about when it comes to punching presses.
Metal stamping and pressing methods
In metal pressing, the material may be stamped into a particular form, or a certain shape may be punched out of the sheet. These are just some of the techniques that can be used:
· Punching – removing a slug of metal that is recycled for another use
· Blanking – shearing out a flat shape which is a desired 2D final piece
· Embossing – pressing a shallow depression into the metal for a raised or recessed design
· Bending – folding the metal along a single axis to form an L, U, or V shape
· Flanging – bending along a curved edge to create a flange or flare
· Coining – compressing the metal into a pattern with flattened edges, like coins
· Hemming – folding the bottom up and back to create a stronger edge
· Deep drawing – stretching the metal to a depth exceeding the diameter
Once the formation stage has been completed, the pressed metal might require further finishing to improve aesthetics and functionality, such as removing rough edges and excess material. These processes include deburring, tapping, and counterboring among others.
Different types of stamp presses
Though all stamp presses more or less do the same thing, there are different ways of doing it and powering the machine. These are the common types of punch press machine:
· Mechanical – includes a flywheel powered by a mechanical motor
· Hydraulic – uses cylinders with pressurized fluid
· Mechanical Servo – faster high-capacity motors instead of a flywheel
· CNC – computer numerically controlled for precise automation
There are different die stamping techniques in addition to varying power mechanisms, including:
· Progressive stamping – the metal progresses horizontally along a sequence of carefully aligned dies, with the final die punching out the finished part
· Transfer stamping – similar to progressive stamping, but the part is punched out earlier in the process and transferred to another station by conveyor belt
· Four-slide stamping – a multi-slide technique for complex parts, shaping the metal with 4 tools simultaneously instead of using dies
As you can see, there’s a lot more variation in stamp pressing than you might have thought.
Types of metal used with punch presses
To go through a stamp press, metals must be thin and flexible, in sheets, strips, or coils. The purpose and required shape of the part will determine which metal is best for the project. Carbon content is one of the factors that affect the formability of the metal. Here are some examples of metals that can be used to create stamped or punched pieces:
· Precious metals (silver, gold, platinum)
· Ferrous metals (including iron-based alloys e.g. stainless steel)
· Non-ferrous metals (aluminum, copper, bronze, zinc, brass, nickel)
· Non-standard alloys (e.g. beryllium copper, beryllium nickel)
Precious metals are obviously very expensive, so ferrous (iron-based) metals are commonly used to keep production costs down. Non-ferrous metals like aluminum and copper are also frequently used for their hardness and high tensile strength.
What industrial stamping presses are used for
There’s a vast range of applications for stamp pressed metal parts, which is why they’re used in such a wide variety of industries. These are just some of the common uses for stamp pressed parts:
· Home appliances
· Medical equipment
Stamp press machines can be used to form large parts for industrial machinery or micro-precision tiny parts with lots of detail. From washers and brackets to electronic terminals, many of the items in your home will contain components that were formed using a stamp press.
Lower costs, high automation, and durable products make this process the most preferable option when large quantities of high-quality pieces in specific shapes are required in short periods of time. So there you have it – that’s how stamp presses work, what they’re used for, and why they’re so important in manufacturing around the world.