This blog is going to be slightly different from the others.  We’re going to talk about a weld process variable as the primary consideration and work backwards into effects on the work piece.  Rather than what directly affects you, I’d like to talk about what challenges us, the welders.

Today’s topic is shield gas.

What is it?  It is an integral part of most atmospheric weld processes (laser welding, TIG, MIG, plasma arc).  It is used to displace the reactive gasses found in the air we breathe.  Oxygen, nitrogen, and carbon dioxide, to name a few.

“I can’t possibly assemble this product with a weld.  It’s too sensitive to heat.”

Really???  Tell me more.  This is probably not the problem you think it is.

It’s almost the Fourth of July, and before we all head out to celebrate with fireworks and barbecues, I thought we’d do something a little different to kick off our first video blog.  What’s the perfect song for Independence Day?  The “Star Spangled Banner” would be a pretty good choice, right?  Well, how about the “Star Spangled Banner” played by a high power industrial laser! Check out the video below:

Oh boy.  I’m sure I’ll get flak from someone for tackling this one, but here goes anyway.

Let’s talk about tolerances for welding.  For this post, we’ll focus only on the weld joint and follow the common theme of customer-vendor interaction.

Customer: “What kind of gap range can you tolerate in a weld?”

Vendor: “What kind of weld?  Process? How deep? How wide? Material?  Filler?”

Customer: “That doesn’t matter yet, I just need to know how big of a gap you can weld and how much it can vary.”

One of the most dreaded phrases we can hear on the welding job shop side is “Just weld it.”

This is a trap, no matter the good intentions behind it.  It's also a recipe for disappointment and hurt feelings. To avoid that disappointment and save some time, money, and aggravation on your welding project, let me explain.

We’ve touched on some pretty heady stuff in the past couple of blogs, so maybe something more straightforward is in order.  Here goes:

Why use laser welding?

I mentioned in blog 4 that contamination is a topic in itself.  Well, why not follow that train of thought?

Anything and everything that is not the “stuff” being welded is a potential contaminant.  Whether it be oil from machining, paper fibers, soapy water from a wash cycle, a sliver of plastic from your expensive non-marring table top, or even brown mustard from that London broil sandwich you had for lunch, these are going to put something unexpected into your end product.

Alright, now that you’ve read the “Misconceptions About Welding” blogs, you want to know what else you might not know about welding, huh?  So, let’s talk defects.  In this blog we’ll discuss porosity.

I like to talk about porosity more than other weld defects because even though there are many contributing factors to it, at the end of the day it is always (did I use an absolute?) trapped gas in the solidifying weld.

To go along with the last post on welding myths and non-weldable materials, I also often get grudging calls from a designer who has been “forced” to add a weld to a design.

Customer: “How much do I have to overdesign this part for this weld?”

Me: “Why do you want to overdesign?”

Customer: “Well, the weld is going to weaken the part!  I need to beef it up to compensate.”

This misconception about welding comes up far more often than I’d like.  An engineer calls in a rush to get a prototype stainless steel part welded.  To save time and cost, he had the parts made from free machining material.  Frantic on the phone, the conversation generally goes something like this: