If there is one subject that gets mentioned with great frequency on the shop floor at machining companies, it is the topic of “making rate”. The run rate or its more formal name “production rate” is the number of parts that can be made in a given period of time. Your success as an operator depends on your ability to make rate.
Let’s start with how the rate of production on a certain part was developed. For any part, the following factors are taken into consideration:
1) Load and unload
2) Machine cycle time
3) Efficiency
Load and unload
If running a vertical machining center or a single spindle lathe there is a certain amount of time it takes to open the machine door, blow off chips, load the fixture, vise, or chuck, close the door and then hit cycle start. That is the load/unload time. I’ve seen that amount time be less than a minute on a simple part, to almost five minutes where multiple vises or complex fixturing is involved.
If you are operating a multi-pallet machining center, the load time is zero due to the fact that while a part is being machined on one pallet, you can be loading and staging the other pallet during the machine cycle.
Cycle time
This is the amount of time from when you hit cycle start to when the machining cycle ends. This is pretty cut and dry. It can be twenty seconds, it can be two hours. It all depends on part complexity and the amount of machining that has to be done. I find that the longer the cycle time, the easier it is to make rate.
Efficiency
Companies allow a certain amount of time to cover the fact that inserts need to be changed, certain inspection outside of the cycle time may have to occur, as well as for breaks and/or lunch throughout the day/shift. This number is expressed as a percentage and will be factored into to the total time to yield a part.
Here is an example that will relate everything that was discussed. We are going to be operating a vertical machining center with a vise. We will be loading a piece of steel that requires some milling around the edges and four drilled and tapped holes.
Let’s determine the production rate. It was determined that the load and unload could happen in one minute. The cycle time was five minutes. And we set the efficiency at 80%.
Load and Unload: 1 Minute
Cycle: 5 minutes
Efficiency 80%
(1 minute + 5 minutes) / 80% = 7.5 minutes
Since we have 60 minutes in an hour we can divide 7.5 minutes into 60 to see how many parts per hour we can make.
60 minutes/7.5 minutes = 8 parts
We have 8 hours in our shift.
8 hours x 8 parts = 64 parts
It would be expected that you should yield 64 pieces per shift.
Occasionally there may be reasons that achieving rate is unattainable. That can involve tooling problems, quality issues, or unexpected machine maintenance or downtime. However, day in and day out, it is the expectation of management and shop supervisors that the production rate will be met.
Advice and tips on making rate
Now that one understands how the rate was established and calculated, here is advice on how to make rate. These are things I learned through the years that have helped me on a daily basis.
1) “You gotta wanna!” What does that mean? It means that rate needs to be important to you and you need the desire inside of you to make rate. It all starts there. You need to be driven to achieve it and make it a goal to achieve every day.
2) Be at your machine. It’s simple. If you are at the machine immediately when your shift starts, after break, after lunch, and all through the day, odds are great that you would have made rate. Many times when a company notices low production levels and begins to look closer, they notice the operator or machinist is not at their machine on a consistent basis.
3) Don’t just go through the motions. You need to have your head in the game and be working in the moment. You need to be focused and thinking about the task at hand.
4) Keep up with the machine! Never make the machine wait for you. If you know your cycle time and have established a rhythm this should not be a problem. Be in front of your machine, ready to change the part, or make sure your pallet is staged and ready to go immediately when the cycle ends.
5) Rate is the result of the work you do all thru your shift. When operating a machine you need to have a conscious awareness of your production level throughout your shift. I found it easiest to link it to various milestones or times of the day. If you are expected to make 120 parts per shift and your shift starts at 6:00am, you need the awareness that by break time at 9:30am I should have about 52 parts done, by lunch at noon, 90 pieces done, and by the end of your 2:00 pm shift 120 pieces complete. When I was running smaller parts I would group the parts in “hourly batches” of say 4 hours or so. That way I’d know how I was doing midway thru my day and at the end of my day.
6) Have self-awareness. Before your supervisor questions you about rate, you should be questioning yourself. If you came up short ask yourself a simple question…why? Was I not at my machine after break when I should have been? Was my machine waiting for me? Was I having tooling trouble? Did I encounter quality problems? Having an understanding of what happened can help you understand where improvements can be made, as well as show your supervisor that you understand what is going on during your shift.
