Solution for identifying missing components

[venkatg2]

Presently we build starter motors comprising of about 8 major sub assemblies and 20 and odd loose components like washers, shims, fastereners, circlips etc.

We have difficulty in identifying the missing parts after assembly.

Can some one suggest or recommend or share their experiences in identifying missing parts ?


V Venkatesh

 

[FrenchCAD]

My experience at Goodrich :

We have a listing in which all and every component of our servocontrols is identified by an ID number. Our technicians have to prepare all parts they need to assembly the servocontrol, then, while assemblying it, they check every part they use on this listing. So we reduce the risks of missing parts, but it is of course a very annoying process.

FrenchCAD
Goodrich Actuation Systems France
Airbus A380 group
cyril.guichard@goodrich.com

 

[ornerynorsk]

What kind of volume are talking about? I would suppose that this is automotive, and you would like something a little more efficient and foolproof than a cursory visual inspection. To be honest, dealing with the missing components dilemma begins long before you begin assembly. The setup of your assembly line, workflow, and operator training could nearly eliminate your need for a post-assembly inspection. IE- if your system is setup properly, the only way that a product would advance on the line is to have received its components from that station. Operator training and keeping your people happy should reduce the risk of deliberate ommission.

 

[MadMango]

If it's not high-speed assembly, you may be able to get away with simply weighing a known good assembly, and use that as a reference. You'd have to get a fairly accurate scale, but after that it should be easy to tell if a washer was missing due to the change in weight.

Wanna Tip? faq731-376
"Probable impossibilities are to be preferred to improbable possibilities."

 

[borjame]

Our company has build boxes that are shrink wrapped (low volume production). The build box has individual compartments shaped to each component so it's very easy to see that all the parts are there (loose washers, bolts, rivets are another matter). The build area is kept VERY clean so the only thing on the bench is the build box and tooling fixtures. All build tools are kept in tool boxes with their own compartments similar to the build boxes (this helps keep down clutter on the bench). When the build box is empty and the bench is clean, you should have a finished product unless someone walked off with a detail. The op-sheets have specified steps that verify washers and loose items are used properly, each step gets signed off, so unless the worker is slacking and just things off all at once, things go pretty smoothly.

 

[falcon4]

The big question is:
Do you want to identify a missing part during assembly or check to see if an assembly is short on parts after assembly?

And is it built by one individual or along an assembly line or cell.

Weighing the finished item is fine, unless the smallest clip weighs less than the allowable variation in weight of the final assembly.

If one operator is completing the assembly then a build board is a good approach, Insure that it has a spot for every component. The operator would place the items on the board, Which may be simply a tray with marked compartments, or even a laminated sheet with pictures of the correct part and quantity. After laying out the required parts per the build board, have the operator sign off the part count.

You'll have to decide if you have time to layout parts if you are building to a rate.

If the build is done in a cell or line then have the next operator sign off that he received the WIP assembly into his station completed and ready for his part of the process.

And as always training the operator is important, so they understand the cost to rework the incomplete assemblies.

If there is any conveyance system, vision inspection is a costly option.

Good luck

 

[macvicar]

As stated above, eliminating or reducing the chances of this happening should be done we setting-up the line/cell. In one case, we set-up our line with a sensor on each fastener bin that was tied into our PLC. The PLC needed to see that the sensor was made (when the operator reached in to pick the part) before the tool would be enabled to run. The PLC then needed a cycle complete output from the tool before the next step could be performed. At the end of the process, the PLC won't allow the part to leave the station unless it has received all the required cycle completes. If there are any errors or missed steps, we have audible & visual alarms.
In another case, we have the components kitted in a supermarket and then brought to the line. At the end of the process, there should be no parts left in the kit.

 

[venkatg2]

Thanks for everyone who have replied to my query regrading missing parts.

I would like to add some more points as requested by all of you.

This is a manual assembly process in a cell, where the operator starts assembling the starter motor assembly at station no. 1 and finishes at station no. 16.

We have provided some fatigue reduction items like, fastening using pneumatic screw drivers, clamping using pneumatic applications, moving components/ part sub assembly in trolleys.

An operator will produce around 75 starter motors in a 9 hour shift, and depending upon the demand, we will deploy a maximum of 12 operators in one assembly line .

The total weight of the final product is around 4 kg, so as suggested by some of you, it may not be possible for us to use weight as a measure for checking.

We have about 30 varieties of starter motors assembled in one line. Hence kitting will also lead us to confusions.

We have provided enough training to the operator, but still the missing parts are taking place.

Are there any other method being followed in similar electro mechanical component industry, to identify missing parts.

I would like to thank once again the members for the response, and I would be glad to see much more responses from more memebers of this forum.

Regards

V Venkatesh

 

[MadMango]

Given those assembly conditions, as stated above, I think your best bet at solving your "missing parts" problem is to use a Tracking or Routing Sheet, coupled with more training.

Basically you would create a table, listing Station Number (1-16), Assembler Name, Checked By and Pass/Fail. You should also include date, motor version (possibly as paper color).

After the first assembler does their part, the unit would be passed to the next assembler along with the Routing/Tracking sheet. The second assembler would visually inspect for the fullfilled requirements of the 1st, and sign off the sheet. Repeat the process for the remainder of your assembly line.

Wanna Tip? faq731-376
"Probable impossibilities are to be preferred to improbable possibilities."