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Job Shop Inspection and Test - Where should we establish inspections? Why?

apestate

Quite Involved in Discussions
#11
In the year 3535

How will I determine a sample plan for a part?

Will 75,000 pieces in one lot, one shipment---use a lot number?

What is the simplest way to measure process capability? We're checking parts informally. The quality manager checks every operation once an hour. if they're not right we hold them for rework. We never ship nonconforming unless the customer is more picky than we were, and she is picky. / The reason I want to know process capability of operations is to determine a sample plan that will serve as a guideline for the management. When we initiate a job, we will use the guidelines of our process capabilities to determine the sample plan. The CNC has no problem making threads. The Brown & Sharp single spindle turret automatics that are driven by cams.. it takes skill to get shiny and comfortable-to-grip threads out of them.

If I go AIAG on all of it, excluding SPC & gage capability, how will this prove an advantage to the process?
 

Mike S.

An Early 'Cover'
Trusted
#12
One option to consider, since you make short runs of many various parts, is to consider pre-control for your in-process "inspection" and control and maybe even final inspection depending on your people and culture. Very easy to use, but statistically powerful and well-suited IMO to short production runs of various parts. If you want to have a "final inspection", at least for awhile, or for randon checks to keep people on their toes, you could use an AQL plan. If your customers are currently happy you're doing something right. There are many options for # of samples, OC curves/confidence of the sample, etc. that surely you can find one (or several) to suit your needs and they too can be relatively simple to follow, especially if you ignore the "switching" parts which I would recommend.

JMO.
 

Cari Spears

Super Moderator
Staff member
Super Moderator
#13
atetsade said:
We depend on our hard-*** Army Reservist inspector for all of quality control. She is good. I want to utilize her as a quality manager and I want to utilize the culture of accountability and excellence that is becoming powerful with our machinists.
How's this for coincidence - for two years (1991 & 1992) I was an inspector at a screw machine shop. I also did a lot of the secondary bench operations and ran their chuckers. They had two buildings, they ran New Britains(sp?) at one facility and Davenports at the other.

During this period I was an Army Reservist. SGT. Trombley - E5, Carpentry & Masonry SGT for the Repair & Utility Section of the 301st MP EPW (Enemy Prisoner of War Camp) out of Inkster MI. We held Iraqi prisoners during Desert Storm. This screw machine shop is where I started working right after I got home from Saudi Arabia. (I've since married and become Spears, I used my maiden name throughout my military service.) I did not re-enlist after my six years as I had started a family and a lot of my priorities changed. I ended my military service in 1995.

Anyway, FWIW, this is how they did it back then. They ran mass production quantities in batches. When a machinist set up for the job, he went to the tool crib and got all of the job specific tooling - every job number had a bin in the tool crib - the tool crib attendant was responsible for maintaining the job bins.

An inspector gave first piece approval - 6 pcs 100% inspected. These were kept in a tiny pan with a FPA tag at the machine. The machinist usually kept it on his bench. The FPA is signed off by the inspector.

As the machinist fills up bins, he would place another tiny pan with a product id tag and 6 pcs in it for the inspector for in-process inspection. He numbered the bins in the order that they were run (on the tag). This is how they eliminated having to sort a whole run, they only had to sort where the problem began and later.

The machinist is responsible for checking his own work in accordance with the engineering drawing (the only real work instruction necessary due to the fact that they were all skilled tradesmen - rookies go through an apprenticeship with experienced machinists). Since the machinist has to do this in order to determine tool wear anyway, we did not feel that the machinists in-process inspection results needed to be documented, he initialed the tag in the little pan and also put the machine number. The 6 pcs in the pan were inspected in accordance with the drawing as well. This was also not documented - what I mean to say is that the actual dimensions were not written down on some in-process inspection sheet, the inspector simply signed off on the bin on the tag. Secondary operations were FPA'd and inprocess inspected in the same manner.

At the end of the run, and after parts washing and any outside processes (thread sealant, heat treat, plating), a 100% final inspection report was documented utilizing the sampling requirements dictated by the customer. In the absence of customer dictated sampling plans, we pulled 1-2 random pcs from each bin of the run. All the bins are the same size, but not all the parts, so some jobs we pulled 1 pc from each bin and others we pulled 2 pcs. (This also satisfied the QS9000 dock audit requirements at the time).

Once that run was completed, the job tooling bin went back to the tool crib until the next time it was scheduled to run, and the machinist pulled the next job scheduled for his machine and started all over again.

Does this resemble the way your company does it? We only did the control plan once for each job, when we first got the contract and prepared PPAP's. Then we ran the job for years under blanket PO's with release schedules. Do you run repeat orders, or do you run the job and its done and on to the next? If the latter is more the case, then I would suggest "part family" FMEA's and control plans.

Wow, I shouldn't have had that third cuppa - I'm more longwinded than usual!!
 
R

Randy Stewart

#14
Sums up what we use to do. The only other item I would mention is that the operators also kept an X-bar & R chart to show the run. :smokin:
 

Cari Spears

Super Moderator
Staff member
Super Moderator
#15
Randy Stewart said:
Sums up what we use to do. The only other item I would mention is that the operators also kept an X-bar & R chart to show the run. :smokin:
I should mention that the FPA and inprocess inspection quantity of six was because they were six spindle machines.
 

CarolX

Super Moderator
Super Moderator
#16
just another nickel worth

Just a couple of ideas.

Your a very small shop, so a very simple method can be used for indication of inspection status and for identifying points for inspection..

Note them on your job router with a sign off for inspection...kill 2 birds with the single pebble.

Carol
 

apestate

Quite Involved in Discussions
#17
Thank you for all of your responses and detailed responses providing background and information.

I'm asking you now for further advice on organization and labeling of product and inspection status.

When we have a bucket full of parts, they are identified by a product traveller. This bucket will go to parts cleaning after first operations and that bucket of parts will remain together. Any second operations will be performed, and this sometimes mixes the entire production run together as in a rock shaker. Literally. Especially with third party outsourced operations, treatments, etc.

All of our production traveller sheets get put together and we lose the lot separation.

My question is about these lots. In runs of 75,000 max pieces, do you see a need to break up the run into lots? Is it advisable?

If not, what do we do with our completed job traveller/inspection requirement/inspection status/product identification sheets?
 

CarolX

Super Moderator
Super Moderator
#18
a couple of thoghts

All of our production traveller sheets get put together and we lose the lot separation.

My question is about these lots. In runs of 75,000 max pieces, do you see a need to break up the run into lots? Is it advisable?
For your business, is it necessary to break up the runs? Do you need to maintain tracability back to the original raw material? My guess is no, since you already combine the travelers together.

If not, what do we do with our completed job traveller/inspection requirement/inspection status/product identification sheets?
Will you need to retrieve the information at a later date? If so, you need to keep theses as "records". Our traveler (we call it a router) contains our inspection results, so they are treated as records and maintained as such.

Hope this helps a bit.

Regards,
CarolX
 

Mike S.

An Early 'Cover'
Trusted
#19
Apparently you do not need traceability back to raw material. If you make sure every lot going into the mix is first approved in all ways up to that point, mixing should not be a problem. If you want some limited traceability you could list the lots that went into one "mix" and assign the mix a new lot number. For example lot 100, 101, 102, 103 are all individually inspected and deemed good up to that point. Now, another process needs to be performed and you mix these 4 lots together for the new process, you could call the mix of those 4 lots lot 104, and attach all prior inspection sheets to the paperwork for lot 104. Just one option.
 
M

M Greenaway

#20
No apparently about it Mike.

Traceability to raw material is only a requirement where terms of a contract specify it as such.

Internal controls on traceability are only there to aid positive identification to take effective containment action in the event of a problem. The looser the controls the wider the containment action would have to be. If your product is low risk/value then maybe you neednt have traceability whatsoever.
 
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