how the present a "liner" 2

[ilkea]

hi,

today, I prepared an assembly drawing in which basicly two pieces will be assembled together, the problem is, there should be a liner material in between. The thickness of the liner will be at most 0.1mm. So, what I did is, in bill of material on the drawing I gave the three components, i.e the two pieces that will be assembled and the liner material. But on the drawing I only put ballons to the two pieces, and in the notes I wrote, "before assembling part 2 to part 1, the liner will be applied to the part 1 according to the document xyz. " and I did NOT put a ballon to the liner. And this caused a little (!) argument with my project manager.

So is there a problem in what I did?

because of the argument, I was asked to prepare a formal report on this problem. So I need to refer a standart while explaning this. Could you please help me?

thanks in advance...

 

[ilkea]

THE TITLE SHOULD BE
HOW TO PRESENT A "LINER"

SORRY...

 

[MintJulep]

I don't see a big problem with what you did....

if document xyz clearly identifies things like:

What side of part 1 does the liner go on?

Does the liner go on the entire surface of part 1? If not, then where?

Does a specific side of the liner have to be against part 1?

How does the assembler determine what thickness of liner to apply?

Is there any surface prepartion of part 1 or part 2 before the liner goes one?

Are then any time, temperature or other process constraints?

After the assembly is complete, how can you tell if the liner is there?

Of course all of these questions apply regardless of the existence or non-existence of a ballon on the drawing.

 

[ctopher]

All parts and materials should be listed on a BOM and balloons called out. Materials such as your Liner would be listed including any epoxies, solders, etc. The quantities for these materials can be drawn to show size, listed in weight or AR (as required). These are just some examples.
Ever do any military dwgs? All materials are listed.

Chris
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[MikeHalloran]

The guy who buys the liners doesn't read the drawing notes, and doesn't dig out referenced drawings. Nor should he be expected to do so.

So when your assembly reaches the production stage, there won't be any liners available to assemble.





Mike Halloran
Pembroke Pines, FL, USA

 

[ilkea]

thanks for your replies...

well, document xyz clearly identifies the details.

I agree that all the materials should be listed on a BOM , but does it really necessary to put a balloon for every part/material listed on a BOM??

thanks.

 

[ctopher]

Yes. Have ever assembled something that listed the part but didn't show you where it goes?

Chris
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[ilkea]

thanks chris,

is there a reference document on this?

here another example, say we are going apply an adhesive before fastening it, in BOM we listed all three parts, i.e the part 1 (the body) part 2 (the bolt) and part 3 (adhesive, loctite 410 etc) and in the notes we said
"Before fastening the bolt apply 1 gram of loctite 410 to the threads, then fasten the bolt using ....., the applied torque should be 5 Nm, wait 6 hours before any futher operation"
should I put a "balloon 3" with the arrow pointing the threads on the drawing?

 

[MadMango]

Information like that can get lost in an assembly drawing. Your BoM and associated asembly drawing just defines the components and their spatial relation to each other. If something like torque and Loctite application is critical, you may want to create a new document. They have various names- Process Sheets, Assembly Procedures, etc.

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[MintJulep]

Mike correctly points out that the purchasing department doesn't read the drawings, they just buy what is listed on the BOM. You've got your liner listed, so no problem there.

For things like Loctite I've seen either an item number call-out along with the hardware, or a note with the hardware call-out, or both. The note either needs to spell out the correct process for application, or refer to a document that does. Since you must have the process info, the item call-out seems redundnt, although I would include it.

One other thing to consider is, do the assemblers work to the drawings, or do they work to a work instruction?

 

[CorBlimeyLimey]

There probably isn't a standard which states that, in your situation, what you did was right. Which also means that their isn't one which says that you were wrong.

However, there is the "unwritten" standard that any drawing must contain sufficient "idiot-proof" information to clearly and unambiguously convey its intended message.

I am guessing that the liner was omitted in one or more assemblies & that you are being blamed for underestimating the quality of "idiots" the company employs to assemble its product. Just when you think you have an idiot-proof solution, better idiots appear.

In future drawings, I suggest creating cut-aways so that the liner is clearly visible, even shaded if necessary. If ballooning, either show everything[/i] ballooned or nothing ballooned. No halfway measures. And don't forget you can use Stacked Balloons. (if your CAD program allows).


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[ctopher]

Remember, just call out the parts, where they go, and quantity. Don't call out on a dwg any processes (how it's done). Processes are called out on a separate document. Process specs can be called out on the dwg.
i.e., for epoxies, "Apply epoxy (item 2) between items 1 & 3 as shown". Qty in BOM will be "AR" (as req'd).

Chris
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[ewh]

I have always approached it as Chris posts. In a cad drawing, to keep the BOM associative, we have files for bulk materials and the like that consist only of a point and any pertinent attributes (which will populate the BOM). We place the point component in the area the item is applied, and balloon that point. There is usually a flag note attached to describe the application. This way, it's pretty much automatic and idiot proof.

 

[ilkea]

I'm vere grateful to all your interest and replies on this subject. I think I got the point.

 

[TheTick]

What is interesting is that most of you are assuming the drawing or CAD model drives purchasing. I have never worked anywhere where CAD or engineering drawings directly drove purchasing.

In my last 5 jobs, purchasing was driven by an MRP system like MAPICS or BPICS. CAD systems can populate or even drive the BOM's in the MRP systems, but MRP drives purchasing, not CAD. PArt of the release process is (usually) for the engineer to cross-check MRP versus drawings.

As for your argument with your boss, you may be right, but you probably won't win. It doesn't sound like it's a technical matter anymore.

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[ctopher]

Tick, most purchasing depts DO think CAD drives purchasing. CAD model don't drive purchasing, but what's on the drawings does, to a degree.

Chris
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[MikeHalloran]

Yes, and the MRP Planner who transcribes the BOM from the drawing isn't expected to read the notes.



Mike Halloran
Pembroke Pines, FL, USA

 

[ctopher]

IMO, everyone that touches drawings and works with them in one way or another, should have at least the basic understanding of how to read them...and take the time to read them.
Drawings are suppose to be for communicating to people on how to create a part or assembly, inspect it, planning, communicate and save history of changes. In addition to a drawing, BOM's are for ordering parts, cross ref parts to location on an assy dwg, inspection, planners, stock room and saving history of changes.
Sorry for rambling.

Chris
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ctopher's home site (updated 06-21-05)
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[MikeHalloran]

Agreed ... and in olden days, my company held blueprint reading classes for buyers, planners, and anyone else who showed the slightest interest.

After they downsized ... well, I don't know; I don't work there anymore. I hear they're pretty lean now. At least the survivors say they're lean, and efficient, and just about perfect, except for that market share thing...





Mike Halloran
Pembroke Pines, FL, USA

 

[ctopher]

I tried holding a drawing reading (no more blueprints) class a few years ago at my last job. Two of the employees were inspectors. One asked "Why do some dim's have .xxx-.xxx and some have .xxx?" The other asked "What do all those symbols mean?" Thye told others how difficult the class was, we never had another class!
It should be mandatory to know this stuff when hired!
Sorry, didn't mean to get off subject. Just trying to show how important everything on a dwg is.

Chris
Systems Analyst, I.S.
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ctopher's home site (updated 06-21-05)
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