Machine Design Principle 2 – Simple

In this case Simple means the bare essentials to get the job completed. Most machinery manufacturers create base equipment that has some extras that will never be used in our application, but they are trying to create as much value for a large range of customers as possible. Not only do these “extras” create additional cost, they also must be maintained and at times can even create a downtime issue. If we are going to take the time to create our own equipment, we need to make it as Simple as possible.

When thinking about being right sized, you probably started to break up the work into takt sized chunks. To add simple to the equation, think if the product can be broken into segments that can be manufactured using simple single purpose machines. For example, a series of dedicated table saws and fixtured drill presses vs. a CNC machining center – a series of single axis welders vs. a robotic one. You are probably wondering about flexibility. The machines I am describing are for high volume low mix products that are run daily. Low volume high mix products are better suited for the machining centers and robots. The idea of running the “dogs” on the new fancy equipment is a bitter pill to swallow for many manufacturers, but I have seen many facilities brought to their knees due to creating a bottleneck out of trying to run everything across the latest piece of technology.

Simple single purpose machines are better in these ways:

  • Safer – it is easier to create guards to protect the operator on a simple machine
  • Quality – the tooling can be designed such that only quality parts are produced – Poke Yoke
  • Quick / Zero setup – set up time should be zero to seconds on a simple dedicated machine
  • On time – the line is always ready to run at a moment’s notice – a spike in demand can be overcome with additional manning on the machines
  • Easier to maintain – simple machines are easier to maintain with operators doing much of the TPM – when a breakdown does occur, it is easier, cheaper and faster to repair the simple machine

You will be surprised that sometimes it is more difficult to design a simple machine rather than using a multipurpose purchased piece of equipment. Make sure the machines can run at 80 percent to 90 percent of takt and the operator(s) can make a cycle through multiple machines within the takt rate. This means the machines should be able to run unattended after they have been loaded.

Be prepared to talk with product engineering about some tweaks to the design that will make the product more manufacturable. It may be an additional hole to assist with product placement/detection or a small dimensional change that eliminates the need for another set up. This may be new to them, but  the more  that you and engineering  can engage in a conversation about simple to manufacture parts, the better it will be for the company overall.

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