The cycle time problem
Increasingly often I face the cycle time problem.
If you also work at a foundry you will know well that the end client does not realize how difficult the process is (and he does not care about it either): he only wants a certain number of pieces weekly.
You, as contractor, have to define the process. You have to cast the pieces, finish them and follow up the delivery.
There are innumerable ways how to structure the process.
If you follow this blog you might realize that each foundry has its own work process and for every need there is the correct solution.
This time I want to talk about a more specific matter which is recurring more and more frequently: Deburring many pieces within a very short cycle time.
The deburring cycle time is set by the operations to be done.
If the deburring time is 60 seconds, no trick exists to make a cut in 30 seconds.
What should you do?
There are two wrong and self-defeating approaches:
A- reducing the cycle time
B – Robots handling the pieces
Reducing the cycle time
Sometimes I talk with friends who work in the sector about this matter and I have the feeling that I am telling jokes.
But it is like that!
Many swindlers promise the moon to contractors and they trust them.
Cutting and deburring follow physical laws: There are no exceptions
It is the same if you go to the seaside without sun protection cream: You can tell to your wife that you do not need any because you are a man…. maybe the first day you will not burn, and every thing works fine.
But the second day?
It is clear that the sun does not give any discount!
That is exactly how cutting and deburring work
Robots handing the pieces
The deburring time is 60 seconds, if you take two robots you get 30….
THAT’S VERY WRONG!!!!!
Many improvised casting automatic system builders have not yet understood , or they have understood it well but they see an advantage
They propose a machine to you with thousands of robots handling the pieces.
All looks perfect, it looks quite futuristic…
But there is a problem!
Everything works against you.
All has been done on purpose to make you become a slave of the machine, of the process and of the supplier.
It is difficult to explain this bad trick.
Everything begins like this.
The swindler convinces you that by putting more robots to handle more pieces your cycle time will decrease.
The way of introducing you to the solution is always the same, he tells you with a convincing tone: “Nowadays robots are cheap, it’s better to put one more!”
Then he tricks you about the price. A machine with two robots is cheaper than two machines with just one robot.
Then he explains that you are making a great business deal.
He deludes you that your investment will be less to produce your pieces (and so the returns will be faster).
So you trust him. Then the irreparable happens.
The truth is that these solutions are complex and keep your hands and feet bound to the supplier, giving you a very good price because he knows well that you will give him thousands of hours and services.
If you have a machine with 2 robots handling over pieces you might have these problems:
- unbalanced cycle time: one robot is always faster than the other, so you have countless waste of time.
- low accuracy rates; when leaving and retaking the pieces, the gripper always blocks them differently. So your work is never well centered.
- wasting time: Every time the robot picks up and leaves the piece precious seconds are lost. If you have two robots which pick up and leave the piece, there are even more precious seconds lost.
- difficult machine management: your programmer must always remember to keep the processing time of the two robots balanced. So if you have to add a deburring programme because your mould has been damaged, you have to add something to both robots. This is really difficult. if your programmer is not clever enough (and he must really be in this case), then he will make your machine less profitable and you will be forced to pay an outsourcing programmer.
- low efficiency. If you have a problem with the robot, the entire production will stand still. If you have to modify the programme, it will be long and complicated. If you have to change worn tools, you need more time. Everything works against you.
Finally the solution is neither in the cycle time reduction, nor having multiple robot systems.
So what do you have to do? You have to do simple, trustworthy and repeatable things.
if the cycle time is 60 seconds and you need a piece every 30 seconds, just instal 2 simply identical machines.
Independent and simple machines mean:
- easier to use
- more efficiency
- more flexibility
- low piece cost
All features in your favour.
- Easier to use
Each machine is independent. If you add a deburring operation you have to add it to the robot programme, you do not need to think about which robot is better to use. Or how you may balance the cycle time. You have just to add it and that is all.
- more efficiency
Because you do not waste time in taking and depositing pieces or asynchronisms between the robots, the work cycle is more efficient.
Then if a machine stands still because of programming or for what ever reason the other one goes on working.
- Efficiency is really superior.
- more flexibility
Often it happens that when there are more moulds producing the same thing, you might need deburrring programmes for each mould.
If you have independent machines, you can produce pieces done by a mould with one machine and others separately produced by the other machine. Or in the event that you do not have enough pieces of one kind in order to work with both machines you may can produce something else.
- low cost piece
in the end you will be producing pieces in less time with a higher efficiency. So you do not waste money in training workers or buying services from your supplier.
if you think about it, two independent machines cost more than one with two robots…. but only after 6 months the difference has been paid. And you will earn for the rest of your life.