When I am asked questions relating to factory layout the questioner provides me with detail of their existing situation and explains what improvements they are seeking as a result of changing their layout. Improvements such as an increase in throughput, productivity and faster reaction time. In other cases where companies are moving to other premises or want to install new equipment they have this opportunity to develop the best layout possible. Some companies recognise that they can derive a competitive advantage by maximising throughput per square foot of factory space as rents, business rates and energy costs continue to rise. Your question, though, is pointed at the method to follow when reviewing plant layouts, so the answer is along those lines.
Firstly, bear in mind that a factory layout comprises a series of small layouts (processes) involving machines (e.g. saws and welders), manual processes (e.g. assembling hardware to frames), storage area and spaces between each of these processes. Additionally, of course there are rest rooms, toilets and office spaces.
Some very successful manufacturing companies developed the method set out below and is one that I have used many times over the years. Before I go through the method some do's and don'ts.
- Don't set out to simply fill the space available, the further apart your processes and machines the greater the manufacturing time.
- Do take into account H&S regulations including risk assessments.
- Don't think of layouts in terms of regimented lines and patterns.
- Don't formulate long term layouts that accept low productivity or poor machine performance.
- Do involve the people working in the factory, they know what goes on better than anyone else.
- Do ensure that you only incorporate equipment that you need, there is a place for everything and good housekeeping practises are incorporated.
- Do benchmark yourself by setting some targets you want to achieve as a result of the changes. See manufacturing norms section of this website for a series of targets.
To optimise production flow;
- Establish where you are by recording every one of your individual processes on a process sheet. Process sheets describe the operation as it is currently performed breaking it down into manageable chunks. I advise a detail sketch is made of the process. I use a process sheet that incorporates individual operations in the process, a layout, safety instructions and process times.
- Record the time to carry out each of the processes and convert this into throughput expressed as items (windows and doors) per hour. I always check this by recording the actual production per hour over a number of days. This check will show up problems outside of the process such as machine breakdowns.
- Closely examine every process seeking to make improvements and solve the problems that are identified by the actual production records. Additionally, seek to reduce non added value operations such as walking, criss-crossing, double handling, waiting and fetching materials. Where there are a number of people working within a process seek to achieve an even balance of work; I have a simple pillar chart that makes this job easy. After this examination you will have established a new throughput per hour for each process.
- Now combine all the processes onto a factory layout sheet ensuring that the distance between each process is as close as possible avoiding unnecessary walking and WIP. Some people use computer programmes others prefer a large sheet of paper and cardboard cut-outs representing each process. Move the processes about until everyone is happy with the result.
- Having established the output per hour for each process and drawn up the overall factory layout you identify the bottleneck process. You now need to try to open up the bottleneck by going back through the method described above, looking to make further improvements. Also check if you have achieved the benchmark targets you have set for yourself. Only finalise the layout when you are absolutely sure that you have maximised the throughput through the bottleneck process.
This is, and can only be, just a brief outline of the method to use to optimise your factory layout. To provide more help and information call me on 01453 521621 or e-mail me on david@521621.com We also run a Lean Fabricating course where, amongst many other things, we go into this subject in more detail. As part of the course a manual is provided that has examples of all the documents to use. These courses are frequently carried out in-house where we are able to address issues relating to the specific company.
