Hi Brian
Thank you very much for you comments, Points well taken, forgive the length of my response here, but I wanted to respond to each of your points.
The Pick and Place machine �should� be the bottleneck. The reason is in my 20 years in the industry we have been able to relieve every bottleneck in the plant except the pick and place machine, meaning that once the bottleneck has been chased to that machine we have not been able to relieve it as a stand alone machine. This is after we have recovered virtually all down time caused by feeder exhaust and reloads down to seconds and minutes. Maintenance is a separate not easily controllable issue, and tweaking certain jobs is also difficult to control.
Our online calculator that I am pleased you have tried out, is intended to be used in conjunction with our white paper �Profit-Driven Manufacturing�. Actually the process of finding the the first real bottleneck takes some expertise, which is where consultant companies like mine at Bliss industries comes into the picture to help find it and relieve it. You mention about the �company� bottleneck, that is also correct. As you relieve the factory bottlenecks you will create others including a �market constraint� meaning you do not have enough business to support the factory. In this economy I already hear everyone yelling, my bottleneck is the market constraint since most are slow or slower than they would like to be. The key here is for sales management to be involved with understanding that as bottlenecks are relieved in the factory more finished product can be produced by the same staff, which means if you where producing say 100 assemblies per day your true cost is the entire cost of running the plant for the day including labor and materials divided by 100. If you increase output 30 percent in my argument that would increase your output to 130. You then can divide your total cost by 130. Your cost per unit comes down dramatically.
Now take that reduced cost to sales and split the savings with them in the way of allowing sales to increase discounts to win new business that they could not get before as they were not competitive enough. This will relieve the market constraint and make you more profitable at the same time.
Clearly this is an ongoing process, our methods and processes are bases on �TOC� Theory of constraints as written by Eli Goldratt and his book �The Goal� and �It�s not Luck�. Clearly proven in industry to work by Dr. Goldratt.
The key focus must be to continually identify the true bottleneck and relieve it and then do it again, efforts on throughput anywhere else has little or no true impact on the companies profits. Only machines should be allowed to be a bottleneck. If people are, that process needs to be corrected. Again my experience is once you push the bottleneck to the pick and place machine you have all that accomplished. Then if you have the business to support it you put an additional machine on the same line to relieve it until each machine is about the same amount of time. Then its time for a new additional line.
For those that already have a second pick and place machine on the same line will require focus somewhere else.
On your cycle time for reflow and screen printing, perhaps I am not understanding something. The time you quote are extremely long from my experience with virtually all major machine manufactures. The screen printer cycle time should only be the time it takes for the first conveyor staged board that is waiting to move forward and start the print cycle go through its process until the next staged board begins to move. I would not count any other time as cycle time of the printer as when the line is up and running the initial full cycle only occurs once on the first board going down the line.
The same should be true on the reflow oven, one board after another as fast as they come out of the pick and place machine. The conveyor moves at a certain speed through the reflow oven, the actual time from one end to the other may be 30-60 seconds but if everything is running right once the first board has entered the reflow oven the next board should be right behind it at the exact time it takes for the pick and place machine to complete its work.
I look forward to your response to my comments. I really enjoy this forum.
Ken Bliss www.blissindustries.com
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