by Scott Tacheny
Methods to better meet the demands of thick plate fabricating
Fabricators working with thick-plate understand the unique challenges they face when trying to meet the demands of their customers. Creating a quality part can be costly due to slow set-up, secondary processes, and additional equipment. There are tools and approaches you can use though to avoid the setbacks typical of heavy plate punching and forming.
The goals, of course, are to minimize downtime, reduce set-up time, eliminate secondary processes when possible, require fewer operators to complete the job, and ultimately increase production. Whether your application requires you to punch, bend, or complete a combination of both, the following suggestions will help you achieve the results you desire.
Applications Requiring Punching:
Calculate tonnage: It’s a good idea to get in the habit of calculating tonnage whenever the material thickness is outside your normal practice. We tend to base our decisions off past experience, which works when we are familiar with the material, but for unique situations such as heavy-gauge materials, it is best practice to check your tonnage before beginning.
Add a coating: Consider adding a coating to your punch. They can be quite beneficial, especially when your tool is near the material’s thickness in size, 0.280 (7mm) round hitting 0.250 (6mm) material, for example. This can eliminate a number of things, including galling resulting from material adhesion.
Add strength: If you reduce the tools standard straight before radius (SBR) and increase the tool blend radius, you add strength to the tip of the tool but sacrifice some grind life. Adding strength to your tool is obviously an advantage when working with thick materials. You can recover some of the lost grind life by moving from a stripper that is fitted to the tip to a round stripper that goes around the body of the punch or insert.
Upgrade to an insert design: When you upgrade to an inserted design you have more steel type options available to you, which is helpful if your material is either tough or abrasive. A stronger steel type will stand up better to difficult materials.
Bigger is better: Try moving up to the next punch or insert size, by doing so you increase the tool’s body size, which often is a key factor in the tool’s strength as the added mass enables the tool to absorb the shock and stresses from punching thicker material. Remember that when upsizing, the shape should not be smaller than the tool’s shank.
When forming thick material you can consider going to a larger station. Large station tooling allows for more surface and holding force as well as a longer tool stroke.
Applications Requiring Bending:
Increase die opening: When working with thick material make sure you increase the opening of the die. Choose a thicker bodied punch and get in the habit of calculating tonnage whenever the material thickness is outside your normal practice.
Consider heat-treat: Thicker materials can often be abrasive resulting in excessive wear on your tooling. Adding a heat-treat, laser treatment or induction hardening process to your tooling can help to minimize this wear.
Increase punch radius: Consider increasing the radius size of your punch in order to disburse the load across a larger area. This will help reduce isolated tonnage on the punch tip.
In addition to best practices, there are tools that can make your job easier as well. Tools like an adjustable v die, replaceable radius tip inserts, or insertable shoulder dies are designed to relieve the burden that heavy-plate can cause. Requirements for heavy-plate applications are becoming more demanding but fortunately the tooling for these types of applications is also improving. Between proper techniques and specific tooling, heavy plate jobs can be both efficient and cost-effective while creating high-quality parts. SMT
Scott Tacheny is an application specialist at Wilson Tool International, White Bear Lake, MN.
