By: Peter Ulintz, PMA technical director
An important requirement of any die operation is the proper alignment between all the working components. In stamping operations, accurate alignment is necessary to maintain proper clearances between punch and die steels.
Cutting, punching and trimming operations require cutting clearances that are held within close limits. Because many stamping features are not symmetrical or totally round, cutting clearance usually is measured at one side of the cutting profile and specified as a “per-side” clearance. The amount of clearance applied and the sharpness of the cutting steels have a direct effect on the quality of the sheared edges.
When the cutting clearances are small, press and die alignment becomes critical. If this alignment is not maintained properly, the punch and die details may contact each other and the cutting edges may be damaged. Clearances that are too tight will produce an edge defect known as secondary shear - sometimes referred to as a “double-break.” Small cutting clearances also require increased punching and stripping forces to extract the punch point as the pierced material grips firmly around it.
Larger cutting clearances make press and die alignment less critical and also require less cutting and stripping forces. But when the cutting clearance becomes too great, extreme rollover can occur and undesirable burrs may develop. In extreme cases, the metal may actually tear or crack in the rollover zone if the surface is stretched beyond its ultimate tensile strength.
The best way to protect a die from damage is to make sure that nothing is physically out of place during a press cycle. This involves mounting sensors in the tooling and equipping the press with a controller to interpret the signals from these devices. Sensors are proven to reduce the potential for die damage by detecting speed, accuracy, part orientation, feature positions, part presence and part ejection.
<a target='_blank' href='http://ad.thefabricator.com/delivery/ck.php?n=ea3d867'><img border='0' alt='' src='http://ad.thefabricator.com/delivery/avw.php?zoneid=217&n=ea3d867' /></a>
Proper sensor selection, placement and function are critical. Sensors often are placed in progressive dies at multiple locations for critical point-of-operation detection, such as bending and punching, short feed and long feed detection, and monitoring slugs and missed hits. In transfer dies, sensors also are incorporated into the grippers to detect that parts are in place before they are transferred to the next station.
Sensors in stamping dies help stampers reduce downtime and lost production, as well as associated maintenance costs and inadvertent shipping of bad parts.
Interested in learning more about die sensors, controls and punching technology? Register for PMA’s Punch & Die Technology Seminar and Sensor & Control Systems Seminar .
Popular posts from this blog
Guest Blogger Kelly Barner, Editor, Buyers Meeting Point Think globally, act locally. – Paul McCartney …except when to do so causes more harm than good. – Kelly Barner As consumers of goods and services, we are constantly bombarded with feel good messages about the companies we buy from. Green production, sustainability, and local sourcing: it is easy to take for granted that these programs are in everyone’s best interests. After all, why wouldn’t we want the companies we patronize to keep the bigger picture in mind and take every opportunity to do a little bit of good in the process of making a profit? Business to business operations have to take a different kind of approach to such initiatives as their immediate customers are usually more motivated by efficiency and innovation than socially-oriented programs. Procurement and purchasing professionals play a unique role in B2B local sourcing; we have to outline the pros and cons and help the rest of the company dec
President Trump announced via tweet on Monday that he was imposing tariffs on steel and aluminum imports from Brazil and Argentina due to both governments devaluating their currencies. These two countries previously had reached a deal with the Trump administration to avoid Section 232 steel and aluminum tariffs by agreeing to quotas. Both Argentina and Brazil were exempted from the 232 steel and aluminum tariffs in May 2018. The tariffs can’t be “restored” because the two countries were not subject to tariffs in the first place. The exemptions for both countries required Presidential Proclamations, and to change the quotas to tariffs would require new proclamations as tariffs can’t be re-imposed by a tweet. At this writing, we are still awaiting these proclamations. If the President does move forward with these tariffs, it would likely lead to an immediate legal challenge. A current U.S. Court of International Trade case (Transpacific Steel v U.S.) is focused on this exact issue of
On September 24, the Department of Labor (DOL) announced its final overtime exemption rule issued under the Fair Labor Standards Act, increasing the minimum salary threshold for workers to qualify for overtime pay when working more than 40 hours per week. By increasing the threshold for employers subject to the federal standard to $35,568, up from the current threshold of $23,660 set in 2004, the agency claims 1.3 million more American workers will be eligible for overtime pay. The DOL’s final rule, which goes into effect on January 1, 2020, includes: Increasing the minimum salary required for an employee to qualify for exemption from the currently enforced level of $455 to $684 per week ($35,568 annually); Increasing the total annual compensation requirement for “highly compensated employees” (HCE) from the currently enforced level of $100,000 to $107,432 per year; Allowing employers to use nondiscretionary bonuses and incentive payments (including commissions) that are paid