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SHEET METAL FABRICATION PROCESSES EXPLAINED

When considering a Contract Manufacturer for a Precision Sheet Metal Fabrication Process for a part to be fabricated out of sheet metal, you need to know the processes available to understand how you will design your sheet metal fabricated part to be the most economic manufactured. Each process has its positives and negatives.

Many fabricators will force-feed you what is easier for them, not necessarily what is best for your product in quality and cost. Let us summarize the major process;Laser Cutting, CNC Turret Punch Press, Press Brakes, and Traditional Sheet Metal Mold Stamping or Progressive Die Mold Stamping using a mold, pointing out the positives and negatives of the processes together below:

Laser Cutting

Laser cutting is a simple sheet metal fabrication process using a laser to cut a pattern out of a sheet metal sheet/plate. A sheet metal plate is put on a table, and either the laser is programmed to move, or the table is programmed to move to cut the shape required. This is the go-to for many products because it can be quickly and easily programmed from a 2D drawing to cut any simple to very complex shapes.

Positives:

Sheet metal fabricated cuts are smooth, clean, and precise, no or little cleanup after cutting is usually needed.
No tooling is required.
Many lasers can cut from very thin to very thick, 3/8” materials.
Laser cutting can cut Stainless Steel from 1/32” – ¼” depending on the Laser cutting equipment’s capabilities.
Depending on the fabricators and part fabricators laser cutting quantities can be as small as 10 to 1000. however, the sweet spot for Laser Cutting for most parts is 10-250 regarding cost.
Product design changes are easy.

Negatives:

For Carbon steel and aluminum, depending on the complexity and quantity, this can be the most expensive process, especially for quantities of 100 and greater.
The actual cutting time is longer than other processes.
Must use a secondary process to bend the parts, a break.

Summery, if you have a low quantity, very complex shape precision sheet metal fabricated parts, stainless steel material, or thick material, Laser Cutting is an excellent option. However, laser cutting is easy to set up for the fabricator, so be aware they might force-feed you this process if they are not equipped or specialized in other processes.

CNC Punch Press

In the sheet metal fabrication process, the CNC Turret Punch Press process that uses a turret that will quickly change tools to cut the desired shape while normally, the table is programmed to move to accept the punch tool. The CNC punch tool rapidly goes up and down, and nibble’s the cutout. Think of a 2” square hole. You would use a ½” cutter to nibble the cutout along the cut line until the cutout is complete.

Positives:

For the CNC Turret Punch Press, if special tooling is required for clean-cut holes or cutouts, the cost is minimal.
The CNC Turret Punch Press is an extremely quick cutting process.
Design changes are easy to incorporate.
The CNC Turret Punch Press is great for carbon steel and aluminum up to 3/16” thick depending on the complexity of the cut.
Depending on the material’s size and thickness, this process is good for 50-1000 parts but ideal for larger parts, 12” + square, at volumes of 100-1000.
The CNC Turret Punch Press is quick and easy to program from a 2D.
The ability to easily change the design makes this process great for smaller trial production runs to test a product’s viability.

Negatives:

The CNC Turret Punch Press is not efficient when cutting any thickness of stainless steel or Carbon Steel and aluminum over 3/16” thick.
Most CNC Punch Press processes will leave some cut / “nibble” marks, see the picture to the right. However, Ionthis uses special tools and clean-up processes to eliminate such marks. If required, much of this can be removed by process control and hand clean up. Make sure you are aware that most CNC Turret Punch Press will not clean up these marks.
The CNC punch press must use a secondary process to bend the parts like a brake press.

Summery, if you are looking at routine production parts in Carbon Steel or Aluminum between the production quantities of 100-1000 or be able to do design changes on the fly, the CNC Turret Punch Press is an excellent process to use.

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Sheet Metal Press Brakes

When a part is cut utilizing a CNC Turret Punch Press or sheet metal laser cutting, when A bend is required, and sheet metal press brake is used in the sheet metal fabrication process. There are typically 4 types of press brakes, fully manually Press Brake, CNC Press Brake, robotic, and automated to bend sheet metal to various bends profiles and designs.

Manual Press Brake

These Press Brakes are set up to complete only one operation or bend at a time, and then the tooling is changed for the second operation. These Press Brakes are mainly used in the prototype, minimal production, or for hobbyists.

CNC Press Brake

CNC Sheet Metal Press Brakes take a 3D part file where the operator will input the required bends and bend angles in a sequence down the break utilizing preset separate tooling for each bend to complete a finished part. This increases the speed and accuracy of the production.

Robotic Press Brake

This simply a CNC sheet Metal Press Break replacing the human with a robot. The is another step to increase speed and accuracy of production; however there is an increased cost in set up for a Robotic Press Brake therefore, and increase is quantity, MOQ, is needed depending on the number and complexity of bend is required.

Automated Sheet Metal Press Brake

This Press Brake is one system that moves the cut sheet metal part and then automatically changes the tooling and moves the part to the required position. These are used only for parts with and a significant number of bends and with a high MOQ.

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Traditional Sheet Metal Mold Stamping

Traditional Sheet Metal Mold Stamping is a sheet metal fabrication process that requires a mold to be made to replicate the parts. Depending on the exact Traditional Sheet Metal Mold Stamping process, you can punch martial of copper, nickel, aluminum, steel, and stainless steel to great thicknesses. For small, simple parts, a single mold can be used to cut and bend the sheet metal without the need for a press brake.

In Traditional Sheet Metal Mold Stamping, for larger and more complex the part becomes, 2+ molds are used. To increase efficiency over multiple molds, a “progressive die stamping” mold can be used. This is a single mold were a long strip of material from a coil is feed into one end, and as it goes through the mold from one end, the material is punched in steps as it is pushed through the mold at the far end/exit the final step cuts the material off and a finished part is dropped off.

Positives:

A multitude of materials and thicknesses.
Fastest quick production.
Does not need a secondary bending process, a break.
Part edges are cosmetically clean, no extra finishing normally require.
Smaller parts say 2” square; molds are economical.
Most cost-effective with high volumes when you can amortize the cost of the mold over the large volume.

Negatives:

Mold cost could cost from $1000-500K++ especially costly for 12” square and above.
Hard to change the mold if the design changes.

Summery, if you have a high production quantity sheet metal fabrication with a long-life cycle that allows you to amortize the mold cost, this is the process of choice.

Additional Considerations

Other areas in the sheet metal fabrication process you should consider when at your design stage but not limited to are:

Deep Draw, this is where a LARGE press and mold is used to “draw” the metal. This means shape type of metal. Think of it as making a flat sheet into a bowl. This is usually costly, but it is unavoidable but must be in high quantities to justify if it is a must-have shape.
PEM and Fastener installation. This needs to be thought through carefully; when it is a must in your design, consider the cost and minimize the numbers much as possible.
Welding/Joining. There are a multitude of different processes to weld and join two materials together. These include simple rivets, spot/resistant welding, friction welding, MIG, TIG, and stick welding. They will all impact costs differently, so consider them wisely.

Conclusion /Sheet Metal Fabrication Processes

The sheet metal fabrication process comes down to cost depending on your product and quantity. To understand more clearly, think of a 2” x2” x2” open-ended box out of 16 Gauge aluminum. Laser Cutting and Press Brake bend would take less than 2 minutes to produce. On the other hand, a CNC Turret Punch Press and Press Brake Bend would take less than 1 minute to produce. Last, a Traditional Sheet Metal Mold Stamping would take less than seconds to produce.

The last two items you must consider are a “Cradle to Grave” and a FULL-SERVICE COMPONENT CONTRACT MANUFACTURER for the sheet metal fabrication process.

FULL-SERVICE means the contract manufacturer can provide you with a finished part including machining, PEM/Fastener installation, Powder Coating, Plating (anodizing, Chromate, Alodine, and so on) &silk screening/engraving, a “one-stop-shop” This eliminates having to resend out your part for a secondary process to separate multiple vendors. The significant advantage of this is you now only have one source responsible for your quality and on-time delivery needs.

“Cradle to Grave” means as your product matures, we will continually give you suggestions (process changes, material changes, sub-assemblies) to reduce your cost giving you an improved sales advantage. Ionthis can do both!

For a DFM/Analysis of your Sheet Metal Fabricated component or assembly, feel free to contact Ionthis at engr@ionthis.com.