Punching Titanium

October 1, 2010

Processing titanium is still in the early stages of development, and fabricators are always finding new applications for this product.

Forming processes are completed gradually, forming the material in steps to achieve the finished form.

Canadian Industrial Machinery asked Mike Kroll, product manager – TruPunch and TruMatic machines for TRUMPF Inc., to explain how manufacturers can improve efficiency when punching titanium. Here is what he had to say.

CIM: What industries are most interested in punching titanium and why?

Kroll: Fabricators that produce lightweight parts to maintain structural integrity are punching titanium. Fabricators involved in the racing industry are using titanium because of the lightweight nature of the material.

Processing titanium is still in the early stages of development, and fabricators are always finding new applications for this product.

CIM: How does punching titanium differ from punching other materials?

Kroll: Titanium has a higher tensile strength than steel. Titanium is also a more brittle material to punch, which can have an effect on how it is processed on a punch machine.

When punching titanium, fabricators need to apply certain techniques to achieve the best possible finished part quality. Tool lubrication plays a key role in this process to help reduce tooling friction, and forming processes usually are completed using multiple hits or a deep-draw process. This is completed gradually, forming the material in steps to achieve the finished form.

CIM: How do different types of titanium affect the punching process?

Kroll: Similar to different types of steel, aluminum, or any other material, titanium can have various tensile strengths. The machine’s tonnage capacity determines the maximum or minimum hole size allowed when punching titanium. Once any type of form is introduced to the part, the type of titanium used will have a direct effect on the form, size, and height limitations.

CIM: What does this mean in terms of punching speed?

Kroll: Speed is generally not sacrificed during the punching process. Process application factors play key roles during titanium punching. Lubricating the tool, clamping the material with the tool stripper, and, controlling the ram speed, especially with thin titanium, all become integral parts of the process.

CIM: How does titanium affect tooling choice?

Kroll: Solid tools are recommended. Multiple tools, cluster punches, and insert-type tooling can fail prematurely. Whisper or shear tooling, which cuts the material using a scissorlike method, helps reduce tool wear and tool tonnage.

Additional tool coating can be applied to make the cutting surface area harder. Tool coatings also help minimize material buildup on the sides of the tool caused by friction during the punching process.

CIM: How can fabricators improve hole and form quality when punching titanium plate?

Kroll: Just like the punching process for any material, the hole size is going to be determined by the geometry of the punch going through the material. Engineers often design forms with generous radii to prevent the material from fracturing or cracking during the forming process. This gives the material as much integrity as possible during the process.

CIM: How does punching titanium affect the machine and its components?

Kroll: Punch machines should have safety factors built in to prevent excess tonnage, sheet weight, or material thickness. There should be no adverse effects on the equipment if capacities are not exceeded.

CIM: How important is having a large database of materials loaded into the machine control?

Kroll: The machine should calculate the weight of the material being processed and adjust the machine accelerations accordingly. This allows for lighter material to be processed more quickly than heavier sheets.

Also, all machine adjustments are calculated according to the specific material gravity weight. The punching head can be set in increments of 0.001 inch for controlling the depth of tool penetration.

CIM: When should punching be the choice rather than laser cutting or another process?

Kroll: Processing titanium on a punch machine should be considered when parts have a lot of holes or form features are needed. In this context, punching is always the most economical way to process the parts.

If the material thickness meets the machine specifications and the punched edge quality is acceptable, it is always best to use a punch as a way to process titanium.

For more information, visit www.us.trumpf.com.