How we upgraded a rubber extruder machine and gained 30% efficiency

I was hired to overhaul a worn out rubber extruder machine. The company did not want to buy new equipment. The machine was old and therefore spare parts were not available, so I had to design the parts. Consequently, it was a perfect opportunity to upgrade the design.

The infamous, old machine

The machine was near useless at this point; the main bolt had a crack almost to the core, the rubber backed off from the main bolt due to wear, greatly damaging the bearings and the housing was full of deposits... but I decided to try the task as a challenge.

To remove the main bolt, we had to cut it in half with a grinder machine. It was stuck.

Bearings where damaged by the rubber entering into them

The main bolt, before grinding it in half

For extruding rubber it is necessary to heat the bolt and cylinder liner so the rubber is more fluid. It is also a must to cool the excess heath with coolant. You should never use non treated water, because minerals start to deposit and trouble will arise with time. Obviously, this is exactly what happened.

We used citric acid to remove the excess of deposits which would cause difficulties when assembling the machine. Citric acid is inexpensive and not dangerous if used properly.

Using citric acid to remove deposits inside the housing

To seek possible optimization points, I decided to model the machine in Solid Works and then run some simulations. Many parts were not optimized, like the main bolt (which moves the rubber) and the end piece (which acts like a cap).

Before entering in detail with every piece, this is the model of the machine to the present day:

First design for overhauling/upgrading the extruder machine

After running some simulations, I concluded that machines (especially old ones) are not that difficult to improve, because they are usually oversized, and not to mention that wear leads to decrease in the machine productivity. After the upgrades, the machine produces more than 30% more rubber. Money can be saved in materials and energy and efficiency can raise significantly. Also less pieces were off tolerance.

Compare new orange line with the old blue line. The production increased 30%

I will post how did this work follow in future posts.