One concern I often hear when talking to our customers is how they can better work preventative maintenance (PM) and predictive maintenance (PdM) into their operations without creating a lot of machine downtime. Normally, I have a pretty simple answer for that—schedule your PdM and PM into your everyday operating procedures.
When you run a manufacturing business, you have delivery and ship dates that are usually driven by customer need, so you need to have a production plan, which should include your capacity. Capacity is what you can manufacture with the staff and machine hours available to you. For example, if you have five machines and run them 40 hours per week, your capacity would be 200 hours. If it takes one hour to make a part, you can manufacture 200 pieces.
When you set your capacity schedule, start by subtracting the hours needed for normal PM and PdM. Let’s say each of those five machines needs one hour of PM work and 15 minutes of PdM work per week. You need to subtract 5 hours of PM time and 1 hour and 15 minutes of PdM time from your 200-hour weekly capacity to ensure you can maintain your equipment, which leaves you 193 hours and 45 minutes capacity or 193 parts per week. You shouldn’t commit to more production than that.
Here are a few tips for reducing the impact of required maintenance to your capacity:
This will give you additional production hours. If you don’t have off-shift hours and operate seven days a week, these options are not available to you. In that case, you would need to go back to your capacity plan and remove the needed maintenance hours. Remember, scheduled hours are better and more controllable than hours lost due to catastrophic failure.
Here are some ideas for limiting downtime:
Don’t schedule to 100% capacity. Sometimes things happen—people get sick, material arrives late, people take vacations, etc. A good rule of thumb is to schedule your equipment to run at 85 -90% capacity. For example, if you operate a machine 24 hours a day, 7 days a week, you have 168 hours at 100%. If you use 85% capacity, you would only plan on running 143 hours, which gives you time to perform maintenance.
Capacity planning is the calculation of how many production hours you have. To establish your capacity, take your available hours and subtract all times that you know the machine will not be available, including PM, PdM, breaks, setups, changeovers, shift changes, vacations, cleaning, and more. If you do your capacity planning right, you will see that my previous estimate of 85-90% of availability is very close to the hours you will have available to run production.
One thing I learned during my time in manufacturing is that running smoothly without any hick-ups is not something you can count on. Don’t deceive yourself or your customers and promise 100% uptime, as it rarely happens. Realistically plan your capacity and schedule to it. Make sure your sales staff understands this and does not over commit and promise customers product and timelines that your operations can’t meet.
If you still fall short, double check your capacity plan and find out what went wrong. If you have unplanned downtime, address it by using problem-solving tools, finding the root cause of the lost time, and implementing solid fixes. If you have downtime you can’t eliminate, adjust your capacity plan. It is better to be realistic about what you can do than to push your limits and risk losing a customer, endangering your staff, or breaking equipment.
Capacity planning is key to keeping your facility operating at maximum potential. It will assist you in addressing issues that cause you to miss production plans and help you drive operational improvements.