What Size Assembly Press Do I Need?

There are a lot of different presses available, with some presses providing hundreds of pounds of force, and others providing thousands of tons. So what size shop press do you really need? And how do you know? Getting the right amount of force and power for your factory press can help you find the right fit, and save money, shop space, and energy.

What Size Shop Press Do I Need?

One of the first questions that prospective buyers have about their shop press is how much force do they need? Some presses have as little as 150 lbs of force, while the largest hydraulic presses can exert up to 80,000 tons of force. Unless you’re forging stealth bombers, you probably don’t need thousands of tons of force, but there are still plenty of options to choose from. So how “big” should your press be? How much force do you need?

To answer this question, you’ll need to start with a different question first. What are you primarily using the press for? If your press is significantly stronger than you need it to be, it will not only be much more expensive, but it may actually damage the parts or components you’re working with. Of course, if your press is undersized, it may be tough to complete the job, or the press won’t work consistently at minimal operating pressure.

First, consider the following:

  • What you’re primarily using the press for
  • The type of materials you’re working with
  • Floor space available
  • Your budget

Now sure how big your press should be? We can help.

How to Calculate Tons of Force Needed For Your Shop Press

If you have a good understanding of the jobs you’re working with, you can use the following equations to figure out how much force or tonnage your shop press needs to exert. These equations vary depending on the type of job you’re working on, such as round hole punching or square hole punching. With a bit of information about your materials, such as their thickness and shear strength, you can calculate how much force your shop press needs to have.

Keep in mind there are many factors that affect press force calculations. These calculations can give you an estimate, but they shouldn’t be considered exact. It’s a good idea to run a test first, so you can see firsthand which press is best. You’re welcome to get in touch with us and arrange for sending your parts over to have a test performed on a specific press.

Round Hole Punching

Force = 3.14 x Diameter of the Hole x Material Thickness x Tons per Square Inch (Shear Strength / 2000)

Example: Punching 2.0” Diameter Hole in .250” Thick Mild Steel (50,000 psi / 2000)

3.14 x 2 x .250 x 25 = 39.25 Tons

Square Hole Punching

Force = Periphery x Material Thickness x Tons per Square Inch (Shear Strength / 2000)

Example: Punching 2.0” Square Hole in .250” Thick Mild Steel (50,000 / 2000)

(2 + 2 + 2 + 2) x .250 x 25 = 50 Tons

Press Fit

To determine the force required to press fit two round pieces together, like a shaft pressed into a bushing, use the following formula:

F = D x 3.14 x L x I x P/2

Example: A steel shaft 2” in diameter pressed into a hole 3” long. The interference fit between the two diameters is .006”

2” x 3.14 x 3” x .006” x (240/2) = 13.56 tons

F = force required in tons
D = diameter of the part to be pressed in inches
L = length of part to be pressed in inches (the length of the interference fit only)
I = interference in inches (usually .002” to .006”)
P = pressure factor (see table below)

Diameter (inches) Pressure Factor Diameter (inches) Pressure Factor Diameter (inches) Pressure Factor Diameter (inches) Pressure Factor
1.00 500 3.00 156 5.00 91 7.00 64
1.25 395 3.25 143 5.25 86 7.25 61
1.50 325 3.50 132 5.50 82 7.50 59
1.75 276 3.75 123 5.75 78 7.75 57
2.00 240 4.00 115 6.00 75 8.00 55
2.25 212 4.25 108 6.25 72
2.50 189 4.50 101 6.50 69
2.75 171 4.75 96 6.75 66

Choosing a Press Size By Application

The above equation can help you hone in on more exact force and tonnage requirements for your press. However, if you’re not sure about the shear strength of the materials you’re working with, or if you’re working with many different types of jobs, it might be more useful to consider presses and force by application. We are also available to discuss your specific force needs and help you with this process.

Here is a general outline of the most common applications for shop presses, as well as the most common metals you might be working with, and how big your press should be, approximately.

Application Industries Materials Recommended Press
Light assembly, Riveting, Punching, Marking, Staking, Crimping, Forming, Swaging Medical, Aerospace Plastics, Mild Steel, Aluminum, Brass, Cooper Adjustable air press, 1200 lbs to 2.5 tons
Bushing/Bearing Insertion, Stud Insertion, Swaging, Trimming, Marking or Character Stamping, Assembly, Notching, Joining, Forming, and Fastening Automotive, Agriculture, Aerospace Mild or Carbon Steel, Harder Aluminum, Cast iron, stainless steel, other alloys Pneumatic or hydropneumatic press, 2.5 to 15 tons
Bushing/Bearing Insertion, Stud Insertion, Broaching, Swaging, Trimming, Assembly, Notching, Joining, Forming, and Fastening Automotive, Agriculture, Aerospace Mild or Carbon Steel, Harder Aluminum, Cast Iron, Stainless Steel, Alloys Hydraulic press, 20 to 50 tons

Why Not Get the Biggest Press?

It’s tempting to simply get the biggest or most powerful press that you can afford. But, you can end up overpaying for power that you’re not using, and you might be saddled with the upkeep and maintenance of an expensive piece of equipment. If your press is far too strong, it may actually damage the parts that you’re working with, or it may not work consistently if you regulate the press to minimal operating pressure. Very large presses, especially hydraulic presses with high voltage requirements, can be loud, costly to maintain, and provide potential safety hazards that are definitely not worth the extra force unless you are planning to use it.

Instead of choosing the biggest press possible, look for a high-quality press that meets your needs. You’ll be able to stay within your budget, reduce maintenance costs, and, overall, you’ll be able to work smarter, not harder. Consider the difference between a pneumatic press and a hydraulic press as you choose a shop press. Getting the right type of press, as well as the right size, will help you improve your production and efficiency overall.

Not sure what’s the best option for you?