Secondary Operation Drawings
Secondary Operation Drawings
(OP)
Here is my situation:
We have a part that we would like to have machined by a local fab shop or our overeas plant. These sources can produce large quantities of the basic machined parts at a significantly lower cost than our in house machine shop. However, the secondary operations drastically increase the price of the part, so it would be more cost effective to do the secondaries in-house. So we need one drawing that shows the basic machining sizes and one that gives the finished part.
Here is my question:
Is there a standard in existance that defines how the drawings should be organized? For example, should we have two drawings with distinct part numbers that reference each other or should it be one package with multiple pages (Page 1 - Basic Machining or Casting, Page 2 Secondary Operations)?
If there is no standard in existance, what is the recommended approach.
I have done my research and was not able to find anything "conrete". Your help would be much appreciated.
Adam Vega
Securitech Group, INC
We have a part that we would like to have machined by a local fab shop or our overeas plant. These sources can produce large quantities of the basic machined parts at a significantly lower cost than our in house machine shop. However, the secondary operations drastically increase the price of the part, so it would be more cost effective to do the secondaries in-house. So we need one drawing that shows the basic machining sizes and one that gives the finished part.
Here is my question:
Is there a standard in existance that defines how the drawings should be organized? For example, should we have two drawings with distinct part numbers that reference each other or should it be one package with multiple pages (Page 1 - Basic Machining or Casting, Page 2 Secondary Operations)?
If there is no standard in existance, what is the recommended approach.
I have done my research and was not able to find anything "conrete". Your help would be much appreciated.
Adam Vega
Securitech Group, INC





RE: Secondary Operation Drawings
Having a single part number/ drawing set for an item that may be in inventory in multiple stages of completion is just asking for trouble. It will drive your materials management people crazy.
Yeah, small companies do it that way all the time ... until the first time they miss a shipment because they only have semifinished parts in stock, or anger a customer by shipping semifinished parts.
Mike Halloran
Pembroke Pines, FL, USA
RE: Secondary Operation Drawings
RE: Secondary Operation Drawings
To maintain configuration control over your primary-sourced part, I would recommend creating a drawing or document that fully defines the part (with part no.) as you would like to have it delivered. That way you will have no confusion over what is expected of your overseas supplier. You can also control configuration through drawing or document revisions.
The primary-sourced part no. can then be called out as a material on your next assy level drawing, any necessary machining or manufacturing operations can be defined, and it can be assigned a new part no.
RE: Secondary Operation Drawings
RE: Secondary Operation Drawings
Matt
CAD Engineer/ECN Analyst
Silicon Valley, CA
sw.fcsuper.com
Co-moderator of Solidworks Yahoo! Group
RE: Secondary Operation Drawings
fcsuper: Funny you should ask about my company's system! Before I joined the company, there was no system in place. Just a folder on the network with CAD files and a spreadsheet for assigning drawing numbers. No consistent part numbering system, no "used-on", no source control, no BOM's!!! You can imagine what I am up against.
We have since purchased an ERP system (Infor - Visual Enterprise) and I have the enormous task of configuring all (active) products that we make. Assembly components number into the 100's.
I was not involved in the selection of the ERP system, so I am in the beggining stages of learning it's capabilities. It seems very robust, with full-fledged routing capabilities. However, I am not 100% sure as Engineering is not covered until the 3rd phase of implementation. Financials/Customer service will be first (of course), manufacturing will be second, and engineering will be implimented last.
How would this affect your approach?
Adam Vega
Securitech Group, INC
RE: Secondary Operation Drawings
Matt
CAD Engineer/ECN Analyst
Silicon Valley, CA
sw.fcsuper.com
Co-moderator of Solidworks Yahoo! Group
RE: Secondary Operation Drawings
We actually redrew a number of items as 2 separate drawings.
To me you want a separate drawing fully detailing what you get from the vendor so that you have something to specify to and inspect to. Otherwise you're relying on purchasing when they put the order to say something like "we want the item to drawing 1234 but leave of the .25 hole at grid E7, and the surface finish on surface at grid B2" or something like that. Recipe for disaster (although of course it does happen regularly with certain processes such as heat treatment & plating etc). Even if you put the 'external' details on a separate sheet it's confusing.
In my opinion it's best to make a drawing pack that can survive without a specific PLM/PDM/ERP system while taking advantage of its benefits where possible. This way if the ERP/PLM/PDM system ever becomes obsolete/gets replaced or you outsource the entire product etc the drawing itself has all the necessary detail.
I don't think the application you are talking about really suits a source control drawing as such, since you are fully designing/defining the part and maintaining the drawing etc. Source controls are more when the vendor designs the part and you just want some control over what they supply. (This a simplification from memory, for the detail see the relevant ASME spec)
I'd go for 2 seperate drawings. The second one would say something like 'make from drawing XXXXXX' in the material box/note; and would be routed like this in the ERP system. Effectively the second drawing would have a BOM of a single item. As to whether you put a 'used on' on the first drawing is up to you. This is useful information but notoriously difficult to keep up to date unless you have a really good configuration control system.