Scheduling the shop floor is by far the most challenging task for job shops and make-to-order manufacturers. There are many factors that come into play when trying to determine the best possible schedule on any given day. Here are just a few of the challenges for job shops trying to schedule their shop floor and three tips for scheduling job shops.
It all begins with estimating/routing. You must have routers with estimated times for 100% of the jobs on your shop floor. Even if you did not develop a detailed quote with estimated times and bill of materials, you need to generate some type of router for the shop floor. The router will contain each step/sequence that the job will travel through the shop. At each step/sequence you should define a work center and the estimated time it will take to perform that particular step/sequence.
The challenge for a true job shop is the fact that it does very little repeat work so it is very tough to come up with accurate estimated times. Some people will even use the term guesstimate instead of estimate. The rule of thumb when developing routers with estimated times for the shop floor is to use a 90-95% efficiency rate so that your routers have some padded time which would give your schedule some breathing room instead of being so tight with very little margin of error.
2) Material management
Studies have shown that over 72% of late jobs are caused by waiting on material and or tooling. It’s pretty obvious to most people that a job cannot start until the operator has the material on hand. Since most job shops purchase the material for the job and tend not to stock a lot of raw material, it is imperative that the purchasing person has a good idea on what job requirements are needed so they are able to purchase material in a timely fashion.
Material management begins in estimating. The estimator must have a good handle on lead times for material. Is the material going to take 2 days or 2 weeks to arrive on my dock? The good estimators will send out Request for Quotes (RFQ’s) to vendors for not only updated pricing but also lead times on the material. If this data is readily available for the purchasing person, then they will be able to order the material so that it is ready for the saw/shear operator when the job is ready to start.
3) Data collection/labor reporting
Assuming we have routers with estimated times and material lead times for all of our jobs, the last piece of the puzzle is accurate labor reporting with piece counts on the shop floor. This labor reporting should be in real time with a bar-coded data collection system. Unfortunately, manual time tickets with the employees writing their times on paper will not suffice.
There is too much margin of error for manual time reporting and the information is always 24 hours old because most shops will enter those manual time tickets the following morning or the next shift after the work is completed. Real-time data collection will give you up-to-the-minute information for not only scheduling but also job costing and shipping. With real-time systems, employees will only be able to post time to open jobs, not the job that shipped two weeks ago. You will also be able to see actual vs estimates to determine not only if you made or lost money, but at which step(s) the operator went over his or her allotted time. If job shop scheduling were easy, there’d be a lot more job shops doing business. Don’t get me wrong,
I’m all for competition (and potentially more customers for our job shop scheduling software solution), but there are some tried and true axioms that any job shop owner can use to avoid the headaches and profit-draining that usually accompany scheduling problems. Do you have any tips of your own for improving scheduling in your job shop?