Jig or Weld Fixture Design – 12 Questions

What do YOU ask before you begin your Jig or Weld Fixture Design?  Here are some questions to start the discussion.

When you are presented with some product parts and asked to design a fixture or jig so they can be welded together,  what questions do you need answered before you begin?   It is important to get as much information on the project as possible before you even do a rough sketch.

For example:

1) How many parts will be welded together in this one fixture? 

The production planning team will need to figure this out.  The more parts they can fit on one fixture, the less fixtures and operators they will need.  However they need to take into account that if one station in the factory takes longer than the rest of the stations they will be creating a bottle neck that will slow the whole production line.  That could be fixed by having two of the same fixture, or by reducing the number of parts welded together in one fixture.

2) Is there another product line with very similar but different parts that could be welded together in the same fixture with a quick change over?  

Sometimes a fixture can be used for several products.  Just replacing one or two sub assemblies can quickly create a fixture that can run two or more products.    In a future blog we will delve into the different gizmos and tools you can use to make the change over fast and easy.

V-Blocks for two product lines

Designing for two product lines sometimes is easy.

 

 

 

 

 

 

 

 

 

3) Will the fixture be automated or manual? 

Will you be using pneumatic clamps or manual?  What about sensors that will sense if the part is in place before clamping or before beginning the welding procedure?   Will there be forward and back checks?

At Rentapen, our 3D models will show the placement and mounting of the sensors and clamps.  The design must allow for room for the hoses and wires.  At Rentapen we leave the design of the controls and electrical to the experts.  We focus strictly on the mechanical aspect of the fixture.  It is important to you and the team that there is a clear understanding of where your responsibility lies.   Tasks for who is responsible for what parts of the fixture (jig) or robot cell should be clearly laid out before  you begin the design.

4)  Will the fixture be trunion or table mounted? 

Will it be robotically or manually welded?  If it is robotically welded, what are the dimensions within which the fixture must fit?

5)  When is the project due? 

When should the preliminary design be ready for review?  When should the checked drawings be completed?  Is there a set schedule?

6) Where are the welds?

The answers to these question should be on the weld drawings for the product.  Usually, in a well planned out line, there is a product drawing of the sub assembly produced in the fixture that you are going to be designing.  Study the drawing for the location of the welds.   If there is no such drawing, ask!

7) What are the critical dimensions?

Study the drawing and identify those dimensions that are held to a tighter tolerance.   If there are no tight tolerances between welded parts, then the fixture may not require shimming.   It doesn’t hurt to ask to make sure.  Asking before you begin is much more efficient.

8)  Are there parts that could be put on the fixture wrong?

Study the product assembly and see if you may need to error proof the fixture so that the parts can only go into the fixture in the way they are supposed to.  We don’t want them welding something on backwards.

9) Do you have a list of preferred vendors?  Some manufacturers prefer Destaco or Parker for their clamps.  The larger companies always have a list of the vendors they use and the products they like.  For example, Genesis Systems requires all their vendors to use Rentapen’s RAPid Tooling Components (TM) wherever possible to reduce the costs of their weld fixtures.

As a design service company, Rentapen has even more questions to ask.

10) What are your design and detail standards?

We want to match the customer’s standards as best as possible.   We put the drawings on the customers format, and follow their standards.  We ask for samples of good drawings so that we can see how holes are called off and slots and chamfers are dimensioned.

11)  Do you put more than one detail on a drawing?

Some of our customers put everything on the same size format and put as many part details as will fit on D size sheet.   Other customers limit it to four details on a D size sheet.  And some customers like to have each part detailed on its own sheet.  A B C D or E.

12) How often do you want status updates?

For smaller fixtures, you will design it up and only have them look at it once before you start detailing it.  But for larger projects, usually the customer will want to see your progress once a week, or as you complete the design for each section of the fixture.  I use the term customer to mean who you report to, who you are serving, be it your production planning team or your manager … whoever your customer is.   As a fixture designer the best way to reduce costs for your time is to get feedback on your designs before you go too deep.

What questions have I left out?  What else do you ask? 

Please add to the conversation and let me know what you think!

Weld Fixture Design — Product Changes

How do you design a fixture knowing the product may be modified by the product engineers?

When designing a weld fixture, or jig as some people call them, it is important to remember that things can change.  Machine designers need to think ahead and have a standard procedure to follow that will reduce errors and costs in the case of a product change.  Changes can occur during or  after the fixture has been designed.

Often times the product design team is on a tight schedule to begin production of the new product.  They may hand it over to the manufacturing engineers before all the quirks are ironed out of it.  They may still be producing and working with the prototypes, but they need to start getting the factory ready for production.

Click on the picture to watch the weld fixture design video that discusses this further using Pro/E Wildfire 4.0.

 

Manufacturing Engineers,  what standard method of 3D model component location do YOU follow to help you in the event that product changes are made?

Leave a comment, add a question, sign up for future weld fixture education and updates.

Five Pin Pointers

Weld Fixture 101  – Locating Pins

To recap what was said in the video:

Pointer #1 

You can buy your pins from a catalog or you can make your own.  But don’t use the lock screw design for mounting your pin.  We have found they don’t hold up to the hard use they experience in a weld fixture.

Pointer #2

Harden your pins.  This makes it “harder” for the weld splatter to stick to the pin and easier, then, for you to get the part out of the fixture.  In fact, it is good practice to always harden those components that touch the product parts.  You can surface harden, called “case” harden, or you can full harden, which hardens the part all the way through.  Purchased pins are already hardened.

Pointer #3 

If possible, mount  the pin from the bottom with a screw.   If you can’t mount from the bottom, another best practice is to cut a whistle cut (an angle cut) into the base of the pin.  Then use a set screw to hold it in place.

Pointer #4

When using locating pins in two holes in a product part, use a round pin in the first hole and a diamond pin in the second hole.   The diamond pin will allow for some tolerance variations between the holes in the product.

When I say, round pin, it doesn’t mean that you can’t cut off some surfaces of that round pin as discussed in pointer  #5.

Pointer #5

Other cuts in the pin make it easier to remove the product parts from the fixture.  Square cuts or triangular cuts work well and still have sufficient pin surface to locate the product.

That’s it!  If you haven’t already, sign up to be notified when the next blog on Weld Fixture Design is released!

Now for fun, check out the new video we have from Lashy7 singing our shim king song.

The Preliminary Review – Weld Splatter

It’s a jig, it’s a fixture, whatever you call it, it holds the product together while it is being welded or assembled. In this lesson we are going to look at weld splatter and what to do to keep your fixture ( or jig ) functional.

In tip #5 of the previous blog we talked about looking over the fixture design to review efficiency and functionality of the design. You might want to develop a check off list of items you should explore at this stage.

#1 Can you get your part out after it is welded. Remember the splatter!
#2 Can you eliminate any parts?
#3 Can you make any parts with less machining?
#4 To maintain adjustability, what do you need to protect from weld splatter?

Let’s take a look at our simple weld fixture and see if we can improve upon it.

In the short time we have together I tried to be brief and may have skipped over some important stuff. So be sure to sign up for future updates and education on the form at the right. =============>>>

There it is. Now for a bit of light-hearted fun, check out the song video we recently added to our Shims page!

Please feel free to comment or add suggestions for future topics.   I’d love to hear from you!

 

[author][author_info]Susan Straley, aka, Queen of Lean Machine Design, is the President of Rentapen Inc. in Waukesha, WI. She helps manufacturers reduce costs through excellence in 3D Machine Design Services, RAPid Tooling Components(TM), and Just-in-Time Laser Cutting Services(TM). Susan can be reached at 262-542-8891.[/author_info] [/author]

Seven Tips for Lean and Efficient Weld Fixture Design.

This is my FIRST Blog!!!  Yep!  And I am excited because we are going to go over how to design a simple weld fixture.  Then, with each new post we are going to delve deeper.  This is going to be like Weld Fixture Design 101, and then 201 and then 301!  So you may notice that some things may be not quite right in this weld fixture.  In future blogs we will address that.  So sign up to get notified regarding future education and updates.

 Weld Fixture Design is both an art and a science.  We won’t all agree on what is the right way.  I invite you to comment.  This way we can learn together.

So lets get started!

Tip #1  Ask the right questions before beginning.

Tip #2 Start w/ those items that touch the product parts.

Tip #3 Use purchased components where possible reducing time, costs, and errors.

Tip #4 Design in adjustability with shims.

The right combinations of shims will give the ability to fine tune the location of your product parts to .005” accuracy before mass production begins.

Tip #5 Review the design for weld access, efficiency and functionality.

Can you eliminate any parts?  Is there room for the weld gun?  Will you be able to get the parts out after they are welded?

Tip #6  Have the customer or production team review the design.

Make any changes they recommend and get their approval before putting in the holes, shims, fasteners and creating drawings.

Tip #7 Always have someone else check your work.

Get someone else to look over your design and drawings. 

In future posts we will go further into the design, address more complex issues, and continue learning together.

This list of tips is not all encompassing.  Let me know what you think.  What would YOU add?  Which of these tips would you like me to explore deeper first?