Welding Myths Part 1: Welding will distort my part

There are lots of misconceptions about welding that keep it off a designer’s list of preferred joining methods. Over a couple of blog posts, I’ll debunk a few of the most common myths and explain why they aren’t accurate. I hear this one all the time: “Welding is going to distort my part so that it will be unusable!” While there is a relatively large kernel of truth to this statement, the fact is that welding can be, and often is, a highly controllable and consequently, repeatable process.  Therefore, concerns about distortion can be factored in from the design phase and become a non-issue in production.  Plan ahead Let’s look at a real world example:  A designer is looking to produce a small rectangular electronic enclosure.  Some of the requirements are simplicity of design, low cost, hermeticity, and precise finished tolerances (+/- .005” over 6” span). In this case, the designer chose to work with thin stainless steel sheet (<.020”) cut into pieces with the shape of the top, bottom, and sides.  Disregarding weld shrinkage, when the designer sent the parts out for laser welding he wasn’t expecting his enclosure to come back smaller than the original stamped pieces. Cue the frustrated phone call: “Your welds distorted my prototype and ruined it.”  Here’s where the misconception was formed.  Yes, the part as designed ended up unusable.  BUT, had the designer added in just a little extra material to the stamped components to offset the shrinkage – in this case about .005” per weld – the welding process would have brought the part right to the required dimension in a highly repeatable fashion. In fact, this is exactly the solution that was implemented.  Now the designer has met all of his original design criteria while integrating a very cost-effective laser weld.  Many thousands of parts later, the process is still delivering enclosures that meet the stringent dimensional requirements. Check back soon for the next post on welding myths: “If it’s metal, I can weld it.”