Processes of a part

[inventor187]

I am working for a company that is currently implementing Iso 9001 with new management. We have gone from a job shop to a full blown corporation within a year. Our objective is to get an MRP system up and running and it seems like each department has their own ideas and delemas with our current way of business. We are currently having an issue with our simplest engineering drawings. Engineering is currently creating a drawing that has multiple operations (in-house and/or outsourced) to get the part completed, ex. machining, painting, marking detail. This saves the Engineering group time and errors due to when a CN is needed one drawing can be updated rather than multiple drawings for the same part. However, with one basic drawing number it confuses our system and personel which step in the process we are at when dealing with different batched lots. I believe each process of the part can be entered into the MRP system creating the BOM which will lead to the direction to follow. However I have been given two options, one is to create different drawing numbers for each process of the part or create a suffix for each process and create a matrix table on the face of the one drawing. I am looking for alternative methods and how other companies get around this issue.

 

[drawoh]

inventor187,

One issue with multi-step fabrication is that we will take the same basic part and perform a different step on it. You design a part that is to be machined then painted black. I want some of them painted metallic day-glo puce.

In this scenario, you need a part number for the unpainted part, a part number for the black part, and a part number for the mauve part. It would help to have separate drawings for each step, although, you can tabulate the paint finishes.

My quick and dirty test for combining fabrication and paint would be whether or not I can reliably get painting done by my fabricators. If paint is a separate step and vendor, I want separate documentation. Intermediate part numbers are absolutely necessary.

I have been through the implementation of MRP, as well as a PDM system. Any database requires a lot of teamwork by everyone in your organization. Anyone who sits in his cubicle and thinks he can do his own thing, oblivious of the rest of the company, will wreak havoc on your process.

JHG

 

[JMirisola]

Work backwards. Part 1234 is a 12" x 12" x 1/2" plate with 6 threaded holes, painted blue. To get to that finished part, an outside vendor cuts and taps the plate. Therefore it would have a different part number (2345). While the drawings would look almost identical. The drawing for part 1234 would stipulate that you use part 2345 and paint it per <in-house paint spec>.

There are innumerable variations of this, but all you should have to worry about is the part that is coming in, and whatever processes you need to do to it. Obviously there are exceptions to this, but you don't want to be micro-managing out of house parts.

Jeff Mirisola, CSWP
Design Manager/Senior Designer
M9 Defense
My Blog

 

[MadMango]

The same can be said of the reverse. If you purchase a box with a lid and have to add holes (in-house op) to it, then the purchased non-modified box & lid would be one number, and afterwards, the reworked lid and box would have their unique numbers.

"Art without engineering is dreaming; Engineering without art is calculating."

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[IRstuff]

Going off the last two posts, if you want to avoid different drawings, you could potentially designate in-process identifiers as drawing#step_number, which would make your MRP system happy, and your drawings would have a note about the part identifier changing at each step.

TTFN

FAQ731-376

 

[inventor187]

We have over 20 years of drawings that are implemented with mult-steps for each fabricated part. I would have to think with the small crew of engineers it would be overwhelming to not only create all those extra drawings but also to control them as well. We do have suffixes to add onto the part number if it is being modified as MadMango is suggesting with the box lid and addition of holes. I'm looking for insight on possibly how to get around the situation with our current methods.

 

[rb1957]

typical engineering problem ... what's easy for one doesn't fit easily into another part of the process.

a typical solution is a planning department, that takes the engineering drawings and breaks them into manufacturing pieces. At the end of the manufacturing (and along the way as necessary) the part is inspected to ensure it meets the engineering intent.

the other typical resolution to this problem is politics. at one time enginering rules and does things to suit engineering, then there's a sea change and maunfacturing rules and makes engineering do it in a way that suits them; at another time programs rule and no-one is happy !

 

[micalbrch]

Create different part numbers for each step of manufacturing. All these part numbers refer to the same drawing no. That's how we do it. You avoid making new drawings and "only" have to create new part nos. That's work, too. But new drawings take more time.

 

[mcgyvr]

I've done it multiple ways...
#1-I simply make page 1 of my drawing show operation 1, page 2 shows operation 2, page 3 shows operation 4,etc... Each page has a view label called "operation 1" or 2 or 3,etc...

#2-I have also done it where each step is a different part number.

To me it comes down to how it gets handled as far as job orders and if you are going to stock the parts after the first operation and let them sit for months before operation 2 is completed,etc.. or maybe part1 operation 1 gets used to make part1 operation 2 and maybe part2 sometimes.

as far as ISO is concerned as long as what you really do is what is documented in your ISO procedure you are good to go. Many people think ISO forces you to do something one way but it's all about simply documenting and repeating what you do not trying to make you do it one way.

 

[MadMango]

Typically in an ERP or MRP system you will have access to Routings, or process steps. For a part, the Routing may look like:

5 Material Issue
10 Band Saw
20 Turn (Lathe)
30 Thread (Lathe)
40 Tumble Deburr
50 Inspection
60 Power Coat Black (Vendor)
70 Inspection Receiving
80 Warehouse

Is this what you are looking for? Your process isn't that clear to me.

"Art without engineering is dreaming; Engineering without art is calculating."

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[inventor187]

I tend to believe we will be moving forward to the way micalbrch describes his approach with part number suffixes to each process of the drawing. The big part we were missing is the Parent/Child relationship in our BOM to indicate what level of the part we are at for each build/lot. It was one thing for Engineering to walk the drawings thru each step. However, with manufacturing being a large part of us growing to the next level it is pertinent that Engineering and production can stay productive with minimal paperwork relying on the collaboration of our groups and the implementation of the MRP system. I appreciate all your assistance on this thread. Lets hope I can push the idea thru with minimal pain! Thanks Again

 

[KENAT]

First let's be clear, what your MRP system sees as a 'unique part number' may not correspond to a 'unique drawing' and may not correspond to a unique 'final part'.

Classically, an engineering drawing defines the finished item and rarely goes into details of how to get there unless it directly affects performance. There are some arguable gray areas but it was a principle in the UK, and it's a principle here in the US - it's even in ASME Y14.5M-1994. So none of this routing stuff should probably be on the drawing.

There are cases where different part numbers correlating to different drawings are appropriate, where the end item is different - such as the paint example drawoh gives.

There are situations where it can make sense to have a couple of drawing levels, such as a 'cast part' and then a 'machined part' made from that cast part.

However, most of the time you can have a single drawing for the finished item and single finished part number.

Having some kind of list of 'part levels' corresponding to how far through a manufacturing process a part is, entirely internal to your MRP or equivalent system, may be entirely appropriate. Doing this in a way so that you get a 'report' from you MRP system on what operations need to be done on a part to get from one level to the next may be entirely appropriate. The type of thing MM shows is how I've seen it done.

The 'report' from the MRP system can be attached to your PO's to vendors so that they know what to do. It's very common for some operations to be done internally, and others at separate vendors. Even places with a big machine shop may send parts out for heat treatment, finishing etc.

One area you may sometimes be able to save hassle, say you have a part that is machined & then anodized. Maybe for now you get the machining done at vendor A, and then get the part in, and then send to vendor B for anodizing. Why not order the part complete from vendor A and make them responsible for getting it anodized. You can always require approval of subcontractors in your PO, or even explicitly say they must use a certain vendor etc.

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