Grinding Components

Reading through my reviews of garbage disposal units you’ll see that I focus on the power of the electric motor in the device, together with information about the quality of the grinding components. For this article, I thought it worth explaining some of the basics about the components inside the disposer – why they’re important and why I focus on their build-quality!

From a user’s point of view, it’s easy: you push food waste in via the sink and ground pulp is pushed out into the plumbing and sewage system. In between these stages, the disposer is hard at work chopping and grinding the food waste using a number of metal wheels that spin at high speed to break up and crush the waste.

I’ve found that cheaper disposers use galvanized steel grinding wheels whilst the more expensive units have stainless steel mechanisms, but there are other important differences worth looking out for when you’re choosing your disposer.

  1. Grinding stages: Most manufacturers show the number of grinding stages that are used in a particular model – some models grind the food in a single stage, others have two or three stages, each with different sets of spinning wheels.
  2. Grinding materials: As I mentioned earlier, the wheels are made of steel, but the type and finish of steel will often determine the cost and durability of the unit.
  3. Grinding chamber: Sounds like a chamber of horrors, but the material that is used inside the disposer to hold the spinning grinding wheels is important since it can effectively reduce the noise of the unit when it’s working.

Let’s look at all three technologies:

Grinding stages

This defines the number of different sets of spinning grinding wheels that are used to crush and grind the food waste into pulp. Basically, the more stages there are the finer the waste is before it’s passed into your sewage system.

One Grinding stage

inSinkErator badger 5The cheapest models available generally only use a single grinding stage to chop and pulp the food waste. This means that the disposer can’t deal with some of the toughest food waste, and the unit will need a lot of running water to help wash through the unit and clear the waste. The advantage is that it’s cheaper to produce this type of unit so for small apartments or light waste disposal, it’s often a cost-effective choice.

You’ll find single stage garbage disposers are the least expensive but can’t deal effectively with bones, corn cobs or other tough waste.

A good disposer that uses a single stage grinding setup is the InSinkErator Badger

Two Grinding Stages

inSinkErator Evolution Compact 3-4A unit with a second grinding stage uses another set of steel wheels to crush the waste into finer particles: the material from the first stage that’s already been partly broken down is now liquefied.

A second stage helps to reduce the size of the particles of waste and normally reduces jams that the device will suffer. You’ll be able to feed tougher waste material into the garbage disposer without it jamming.

A good disposer that uses a two stage grinding setup is the InSinkErator Evolution Compact

Three Grinding Stages

inSinkErator Evolution Excel 1A disposer that features three grinding stages normally has a slightly different setup for the first stage – where the wheels cut and chop the waste, then the second and third stage wheels sets grind the waste into ever-smaller particles. Although this type of disposer is more expensive (it’s got more mechanical components inside it), you’ll find it can effectively deal with any food waste without jamming.

A good disposer with a three stage grinding system is the InSinkErator Evolution Excel.

Grinding Wheel Materials

The materials used to manufacture the grinding wheels are very important to their lifespan as a key component of the disposer. Cheaper units often use galvanized steel but the stainless steel used in more expensive units will last longer and stay sharp (and so remain effective at grinding) for longer.

Grinding Chamber Materials

The last part of the equation is the material used to surround the grinding wheels. If you take a set of metal wheels and spin them at high speed, they make a lot of noise. To try and reduce this, the top-of-the-range disposers have double-wall grinding chambers to reduce the noise. Another popular material in more expensive disposers is low-friction nylon (or plastic) chamber walls that not only cuts down the noise but reduces the friction as the food waste passes inside the chamber.