Metal Punching: The Complete Guide

Metal punching is a versatile sheet metal fabrication technique.

In this guide, you will learn everything about the metal punching process, including techniques, benefits, applications, and punching forces, to mention a few.

Let’s dive right in.

What Is Metal Punching?

It is a cutting process that involves material removal from a metal workpiece by applying a significant amount of shearing force. This process creates different but simple holes of different geometric shapes on a metal surface.

Metal Punching Characteristics

Can Create Multiple Shaped Holes
Can Create Multiple Shaped Holes

Punch tooling or die are available in various shapes, so you can use them to attain different shaped holes on your workpiece.

Rapid Process
Rapid Process

The punch tooling and the equipment used in this process are set to quickly ensure the holes are created on the metal workpieces.

Cost-Effective
Cost-Effective

This process is quite economical, especially when creating holes in sheet metal or strips average to high fabrication solutions.

Creates Desired Holes
Creates Desired Holes

Punching is designed to create a die break on the sidewall and a burnished region roll-over of the resulting hole.

Determining Force Required For Metal Punching

There is an equation used in establishing the relevant amount of punch force for punching a piece as follows;

F = 0.7tL (UTS)

  • t represents the sheet metal thickness
  • L is the sum length sheared
  • UTS is the definitive tensile strength of the metal

Technically, the design of this operation makes the die and punch shapes influence force during the process. Thus, the punch force increases while the entire material thickness is sheared once during the process. Generally, beveled punch assists in shearing thicker metals by reducing force at the start of the stroke.

Determining Force Required For Metal Punching
Metal Punching Vs. Metal Stamping

Metal Punching Vs. Metal Stamping

Metal punching is a process that uses dies and punches presses to form holes of different geometrical shapes on the workpiece. In this process, the punch passes through sheet metal, whereas the dies on the different sides support the punches to exert more pressure and ensure the metal doesn’t break.

On the contrary, metal stamping is a set of operations to attain specific shapes by incorporating punching. Ideally, stamping involves a series of different metal processes such as punching, bending, drawing, and blanking, among others. It gives metal workpiece specific shapes to the whole piece.

Metal Punching Vs. Metal Blanking

Punching ordinarily involves forming different holes in a metal workpiece. The final product in metal punching is often a bit larger from which the parts get punched. Besides, you can conduct metal punching manually or using tools but mainly machines.

Hence, it is an effective and straightforward means of creating holes in a metal workpiece. On the other hand, metal blanking is a metal fabrication process where the final product is cut out from a larger metal sheet and residual pieces discarded as scrap. Ideally, it is a metal punching process for rapidly producing holes in different holes.

Metal Punching Vs. Metal Blanking
Metal Punching Vs. Metal Perforation

Metal Punching Vs. Metal Perforation

Metal perforation is a forming process that involves stamping, fabrication or punching to create a pattern of holes, aesthetic shapes, and slots on a metal workpiece. This process enhances the appearance of metal sheets and other valuable effects like noise suppression and protection.

You can use various techniques to perforate metal depending on the specific designs you desire to attain. On the other hand, metal punching is technically about creating holes of different shapes and sizes on the metal sheet surface. It mainly uses a punch press and dies that apply force on metal workpieces to produce the various holes and cutouts.

CNC Sheet Metal Punching Vs. Laser Cutting

CNC sheet metal punching uses programmed computer commands to follow the design’s instructions to create holes and cutouts on a metal workpiece. The metal workpiece is placed between a punch and a die where the former presses into the material and pushes excess metal into the latter.

The coding allows the punch to perform the cutting process automatically. Laser cutting, on the other hand, uses a focused laser beam and gas to vaporize a metal workpiece. The beam slices through the metal, and a gas stream blows through the cut section to create the desired cutout.

CNC Sheet Metal Punching Vs. Laser Cutting

Sheet Metal Punching Process

Sheet Metal Punching Process
Sheet Metal Punching Process

The sheet metal punching process often depends on the actual process you use, whether a manual, tool or machine. However, automated machines are commonly used in this process to attain speedy, accurate, efficient, and reliable results.

The process is initiated by placing the metal workpiece on the lower tool, commonly known as the die. While at it, the upper tool known as the punch is pressed against the workpiece with an applied pressing force.

A punch passes downward via one section of the sheet metal and gets into the die as it leaves desired metal workpiece as scrap. It is then separated from a new pattern.

Also, the die provides the ideal support allowing the punch to exert enough force without breaking the metal. Different strokes are usually required once the sheet metal is placed in the machine. Even so, this often depends on the specific workpiece design; hence would need one or more strokes.

The machine has a scraper, which mainly ensures the plate is effectively detached from the punch should it get stuck and lifted after the strike. Punching tools are available in a wide variety and are designed to perform multiple operations. Such operations include creating pre-tapped holes and cutting straight lines.

They also engrave and conduct a wide range of minor bending operations. The sheet metal material is subjected to shearing between punch and dies to punch out a hole. During the process, the sheet metal material is displaced and loosened entirely by material failure.

In essence, it makes it possible for both the punched detail and bore to attain a distinct cut surface evident in punching operations. Punch and die operation form precise, error-free metal parts of varied sizes and shapes as designed.

Factors Affecting Quality Of Metal Punching

Factors Affecting Quality Of Metal Punching
Factors Affecting Quality Of Metal Punching

The notable factors are as follows;

Amount Of Applied Force

Ordinarily, different metals have various structural properties that usually determine the amount of pressure ideal for quality punching. Some metals are relatively soft, whereas others tend to be quite hardy; thus, the amount of pressure used will determine the actual punching quality.

Size/Shape Of Punch And Die Press

Often, you will find punch and die presses in various sizes and shapes based on the overall dimensions and configurations of the desired hole. These elements define the quality since they influence whether the specific material will yield the best results.

Sheet Metal Thickness

In essence, metals with relatively thick surfaces tend to be challenging to attain neat punches since they require more force. Comparatively, thin sheet metals are, on the other hand, easy to punch and attain higher quality finishes.

Type Of Metal

Hard metals tend to be more difficult to punch and achieve better quality finishes compared to relatively soft metals.

Die And Punch Press Condition

Ideally, punching tools tend to wear out with time after performing several strokes. Hence, those in excellent condition guarantee better quality than relatively worn out.

Sheet Metal Punching Equipment

Hydraulic Punching Machine
Hydraulic Punching Machine

It is a piece of equipment designed to perforate metal with square, round or oblong holes.

You may power it by hand pump, gas, air, or a wide range of electric driven pumps.

Punch Press
Punch Press

This refers to a type of machine used for cutting holes for different kinds of sheet metal materials. It is available in different sizes and can be operated manually for simple die sets or largely automated for multi-station turrets.

CNC Router
CNC Router

This highly advanced machine cuts metal materials into required shapes and sizes. It is programmed to run computer software commands and electronics rather than using a direct human operator.

Punching Pliers
Punching Pliers

It is essential hand-held punching equipment used in small-scale and DIY applications.

This appliance has soft-grip handles, steel arms, and jaws. It punches holes mainly in soft metal materials up to 18 gauge or 1mm thick.

Advantages Of Metal Punching

Easy To Make Complex Holes
Easy To Make Complex Holes

The new metal punching techniques tend to be more detailed and sophisticated; hence easy to create even the most challenging and complex holes.

Production Cost Efficiency
Production Cost Efficiency

The technique is an ideal cost-cutting measure since it takes significantly reduced time. Besides, it is speedy, implying fewer laborers, less machine use, and reduced labor time; hence overall expenses drop.

High-Quality Precision Parts
High-Quality Precision Parts

This process allows you to get multiple high-quality pieces, which makes it high-value for businesses that need bulk pieces rapidly.

High Versatility
High Versatility

You can always use punched parts in various applications since the process gives pieces different sizes and shapes.

Metal Punching Applications

Pneumatics
Pneumatics

Metal punching parts have low tolerances and provide easy repeatability of processes, hence ideal for high-speed automatic assembly lines.

Medical Field
Medical Field

Medical appliances and machinery use metal punching parts that combine design and functionality.

Electromechanics
Electromechanics

Progressive dies, multi-cavity dies, and block dies are used in producing different parts, thus handy in Electromechanics.

Small Metal Parts Assembly
Small Metal Parts Assembly

A wide range of components used punched parts in assembling various functional single units.

Automotive Industry
Automotive Industry

Brushless motors, lead frames, and other elements are among the notable parts used in the automotive industry that are produced through metal punching.

Hydraulics
Hydraulics

Connectors, rings, and bearings are some unique pieces produced by the metal punching process used in hydraulics applications.

People Also Ask:

How Does Sheet Metal Piercing Compare To Sheet Metal Punching?

Both are used in metal sheet manipulation, but piercing creates holes in raw metal using sharp tools. On the other hand, punching utilizes a machine and other tools to form metal objects in particular shapes and sizes using a die.

Why Use CNC Punching Machine?

It focuses on attaining excellent accuracy and is thus the most suitable for creating complicated and precise shapes. Moreover, CNC reduces waste produced during punching while offering speed and accuracy.

More Resources:

Sheet Metal Punching

Sheet Metal Stamping Process

Sheet Metal Blanking

Punch Presses

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