Drum Shell

Drum Shell

The drum shell is the plastic shell that contains the drum. The drum is connected to the drum shell through the bearing. The drum shell is what contains all the water and cleaning fluids, as well as where it drains to from the drum. The tubing all connects to the drum shell to both fill it and drain it.

The drum shell is roughly secured in the same place with springs on the top and suspensions on the bottom that provide cushioning so that the drum shell doesn't hit other components and so that the bearing isn't under too much stress.

The method used to manufacture this part of the machine is probably injection molding, as that method is the most effective for a large part with complex elements to its shape such as this one.

Heating Element

Metal heating elements generally are made from nichrome, which is a resistance heating alloy composed of 80% nickel and 20% chromium. Electricity passes through the nichrome and produces heat due to the resistance.

This part is made by pulling a copper wire through a hollow tube of nichrome. Then the nichrome is filled so that the nichrome and copper are bonded together. The whole tube is annealed to relieve internal stress. Finally, the tube is cold worked into shape around a metal tube (that gives it its bend).

Shock Absorber Suspensions + Springs

As mentioned above, the suspensions and springs are what keeps the drum shell in place. The system consists of two components, the hollow shape made of PVC and the stainless steel part that goes into it. There's also a rubber part on both of them that secures onto the drum shell/ casing through friction.

In the suspensions, there is a small slot for air to escape through. A quicker compression of the suspension would cause enough pressure buildup to resist the downward motion and cushion it, but not too much such that the suspensions are rigidly in place.

The springs, on the other hand, hook onto the top of the drum shell and the upper corners of the casing. These serve to provide a constant upward force, keeping the shell in place.

The springs are made of annealed steel (annealing being a heat treatment that reduces hardness, increases ductility, and relieves internal stress) and hardened after fabrication. This process is different from that used to make small springs (where pre-hardened steel is wound up) as the bigger spring would need to be able to have a higher yield point and using pre-hardened steel would not achieve that (due to internal stress).

The springs are placed on top with the suspensions on the bottom, as the main force acting on the drum shell is gravity, which pulls it down. Therefore, the suspensions and the springs work together to resist the force and make sure the drum doesn't fall down (also preventing the shaft/bearing from deforming under work fatigue).