How to plan a machining site in that makes parts for a production site ? 1

[LCform]

For a mechining site that makes tools for production and maintenance, imagine that there is a high variety in the parts complexity and also the priority changes, I mean every now and then, we might have a new problem with a broken machine or tools. While there are some pieces are regular to be made during every project, in such an ambient is it possible to schedule the work of the machining site ?

 

[JNieman]

Yes.

 

[capnhook]

Don't be surprised that you'll need a crystal ball.

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[KENAT]

Think about how independent machine shops have to do it.

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(probably not aimed specifically at you)
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[JNieman]

You can either look at the work load for particular machines, due dates for each job/task, estimated hours to complete, and assess the situation as needed, then assign duties to the machinist/operator/supervisor... or you can use ERP software. Or a combination. Or you can just write things on a whiteboard every morning, and update as needed.

A plant manager I used to work with had a phrase from his time in the Marine Corps he used to apply to his every-day at work: Semper Gumby. A play on the US Marine Corps motto "Semper Fidelis" (always faithful) Semper Gumby "Always flexible" as a reference to Gumby, a popular claymation TV show character who was as flexible as heated modeling clay.

Anyways... make a plan. Have a plan. Communicate the plan. Understand that no plan survives first contact with the enemy and adapt as needed on-the-fly.

You'll learn to assess and apply many other facts you never thought production had to care about, such as:

1) This machine is working on Job-X but it's not very urgent. I just got a super-urgent part to run that this machine could do. If I tear-down the setup for this machine, the re-setup may be 1.5x-2x the initial setup since now they have to 'dial in' the machine on the partially completed part before continuing. Is that cost worth fitting in the 'super urgent' part?

2) I have a job requirement for 15,000 pieces of this thing, due in one month. That is just enough time to complete 15,000 pieces. It will mean I cannot use that machine for anything else for that month. Maybe if I call the customer, I can delivery 5,000 in a month, and 5,000 each month following, until the initial requirement is met, to give more flexibility to scheduling that machine for other tasks.

Scheduling a "job shop" is a fun time. Keeps you on your toes. When I was doing R&D, design, and production (I was a one man machine shop in addition to designer) the requirements for product would often come with a need-date that was measured in hours or days, not months. I'm very glad the shop manager (he mostly managed an assembly side of the shop) helped me learn "Semper Gumby" as a way of life. I was so much less stressed after that. So while I wasn't a "job shop" per se, my "internal customer" essentially used me like one, to the benefit of the company.

It's a lesson in juggling geese. Baby geese - goslings. They (can be) juggled.


The tools can vary. Whiteboards are nice. Spreadsheets are helpful. There is also ERP software tailored for job shop environments that also handles material requirements, inventory management, and some even handle ordering and billing.

 

[tygerdawg]

You don't give much of a description. But it appears what you are describing may fall into the area of "cellular manufacturing."

This is the production function & layout analysis that groups your parts into families of similar features. This analysis is called Group Technology analysis and Cluster analysis. The family groups dictates which machines are used to produce those families.

References: Mikell Groover's textbooks, others.

Further cell layout analysis dictates how the groups of machines are planned. Even further analysis (if it even applies) will cover the scheduling of the parts through the workcells.

References: SME produces a very effective "how to" book on workcell planning & design covering material flows, machine arrangements, etc. Similar topics are also covered in Toyota Production System (Monden) published by IIE & CRC Press.

This is all solid modern Industrial Engineering stuff. It ain't trivial, but it ain't brain surgery, either.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering

http://www.bluetechnik.com

 

[LCform]

Thank you for your great responses

well to explain the work better , the machining site contains variety of machines, around 12 of them, a 3axis CNC , turning and milling machines, saw and a small welding cell

but the parts arriving have a static type, meaning they should remain for the design be ready or be registered in maintenance , and the sequence is random , depending on the urgency, so we don't plan for thousands of pieces , maybe it's even harder

but like 5 pieces of the same part, 15 of another , 1 complex part , another 2 , and so on but they arrive every day, and then you might see some parts are left there for months and the time has not arrived to touch them , and at the same time you don't know when you will get to the production limit and so on

Thank you very much JNieman for your great answer, I check the software, it seems That it has more features, I think I should start learning the ERP, it also contains invoicing. I appreciate your great help

Thank you ty, I checked the book , there was one section that talked about the cell manufacturing management, but there was not much indication about random arriving parts management

 

[JNieman]

The problems you detail about parts tracking and inventory management are largely solved by the most basic organization and tracking. In the USA, at least, it's extremely common for even small business manufacturing to be ISO:9001 certified which includes requirements for tractability. One of the most basic goals to achieve is that any production part on the floor should be readily identifiable - commonly achieved by assigning a "Job number" to it. That job number will reference an entry in a database of all jobs which will point to all other information - work instructions, billing information, revision level, scope of work, part number, due date, etc. In a very-small-quantity job shop environment, sometimes you have to be 'flexible' with such work. When someone brings in a drive shaft and needs it to be built up and turned back to spec, with a new keyway machined in... it's not necessarily something that has a revision level and rarely even does it have a print. But you do what you can.

Just tag the stuff in your shop, put it in a bin with a label, or use a paint marker to identify it with a unique number, and keep a spreadsheet of what that all means, that anyone can look up as needed. Many shops will print out a paper "traveler" or "work order" that stays with the parts with all the above mentioned information so no one has to look it up on a computer. It might even include checklists that a person must sign their name to, noting accurate completion of each step of the work process.

 

[DAVIDZHW]

it's very very flexible and independent by each machine to meet your concern.
But all the machine mush space in around it's beside wall etc for open cover/door for cleaning, maintainence, the roof shall be heigh enough otherwise you have to move machine out of shop in case of broken spindle etc for milling if you're really really think it happen.
Then think of your parts tobe produced, the size,shape could it be handling by standard pallet or your owne standard package. The space around machine should be able to move parts including forklift routine.
Then think of production routine, if you say production vary a lot, I'll suggest put turning in one line, and milling opposite line.
Raw material and finished goods at end side of the line, QC as well.
Good luck!
David