Webinar: Press Theory

Date: Tuesday, September 29th, 2020: 2:00 - 2:30 PM EST

Welcome to the Press Theory webinar. 

Leading the webinar in this session is Andy Neumann, our Fixtured Tool Product Specialist with over 30 years of industry experience at Atlas Copco. In this webinar, we’re digging into press theory, the science behind pressing applications. Andy begins the webinar with basic pressing terminology that is necessary to know. He describes force and newtons (the measurement of force). He also explains the stroke, which is a unit of measurement for the distance, which is linear. We go through absolute positioning and relative positioning, and the two speeds during pressing applications: approach speed, which saves cycle time, and press speed, which offers more process control to the operator. 

Andy then moves into the material science in press. He describes thermal expansion, which is when metal expands in heat or shrinks in coldness. It’s important to keep in mind that different materials expand at different rates. The modulus of elasticity refers to the measure of the ability of a material to withstand changes in length when under lengthwise tension or compression. The stiffer the material, the more force is required to change the material itself. Andy talks about surface finish, which can be measured by roughness, lay, waviness, and flaws. The surface finish has an effect on friction; surface friction will impact the friction on the surface of the part. 

Following material science, Andy goes into joint designs. These refer to the types of fits of the joint. There’s clearance fit, which guarantees joint clearance. The hole size is bigger than the shaft. Transition fit is interference or clearance in the joint, and the hole is smaller than the shaft. And finally, interference fit is when joint interference is guaranteed, and the hole size is smaller than the shaft. Andy then moves into the two basic pressing strategies: pressing to stop/force and pressing to depth/stroke. When you’re pressing to stop/force, your quality check will be the depth/stroke. When pressing to depth/stroke, your quality check is force. Another strategy is to allow the tool itself to control the depth for verification. On this subject, Andy emphasizes that the right tool for the job is important because size does matter.