KitchenAid Mixer Gears: Metal, plastic, or a bit of both?

KitchenAid is a name that needs no introduction. In the last century, American-made mixers have become world-renowned for their eye-catching design, superior build quality, and an endless range of multi-purpose attachments. While KitchenAid makes some of the nicest stand mixers money can buy, they make some of the most expensive ones too. With some of their models requiring bakers to fork out up to $800, they aren’t exactly what you would call ‘budget-friendly mixers’.

The problem is, like most baking appliances, it is hard to know how much you are actually getting for your money. Sure, we can all see the pretty colors and the raving reviews from loyal KitchenAid fans but when it comes to finding information on the machine’s inner workings, or the durability of the mechanical components, finding this information borders on the impossible.

One of the most important features of an electric mixer is its gear system. People often cite that the motor is the heart of a stand mixer, and if that’s the case, then does that make the gears the arteries and veins? 

Over the years, I have heard some people say that KitchenAid gears are made from plastic, which has prematurely caused their mixer gears to shred and need replacing. I have also heard fellow bakers mention that their KitchenAid stand mixer gears are made from metal. So which one is it?

I recently did some digging to learn more about KitchenAid mixer gears. Here’s what I learned. 

Heads up: I’m not an engineer or a mechanic, just an amateur baker attempting to share some knowledge about my favorite baking appliance. If you have any information on the ‘sciencey bits’ I would love to hear from you in the comment section!  

KitchenAid mixer gears: Why do they matter?

Every mixer uses gears to convert electrical energy from the motor into kinetic energy, which is what allows your stand mixer to whip up our tasty treats. The reason why gears are a vital piece of the puzzle is that the process in which a gear train transfers energy – and what material its gears are made from – will significantly impact the output torque, speed, and the overall lifespan of your machine.

There are two ways in which the mechanics of an electric mixer can do this. The most common of which is a belt-driven system, using drive belts and pulleys to connect the motor to the mixer head. The other option, the one that every KitchenAid stand mixer uses, is called a direct drive transmission. This works through the small rotative drive pinion that directly connects the motor to the planetary gears. There are no drive belts within a KitchenAid mixer, and because there are fewer processes, it allows for a more efficient transfer of energy from the motor.  

Okay, so gearing is an important mechanical component in an electric mixer, regardless if it uses a belt pulley or direct-drive transmission. So why does it matter if they are plastic or metal then? 

The material in which stand mixer gears are made from matter simply because they will have an impact on the lifespan of the machine. Every time you use your mixer, especially if you make large quantities of thick batter, it puts strain on the gears driving the rotational motion of the mixer. Over time, the teeth on the gears will start to wear, and eventually, the gears will start to slip. 

When it gets to this stage, you will notice a significant drop-off in performance (and often plenty of noise) and your mixer will likely need some gears replaced. For this reason, metal gears are often preferred by frequent bakers, as it helps our mixer perform at its best, for longer.

The good news is almost every gear within a KitchenAid stand mixer is made of metal. There is an exception to this though, some models use a nylon worm gear.

The KitchenAid Worm Gear

If you hear people talking about plastic KitchenAid gear, they are most likely referring to the worm gear. KitchenAid first started using a nylon worm gear in some of their stand mixers in the 1970s as a fail-safe mechanism to protect the motors in its less powerful machines.

In the event that you accidentally overload the motor, usually caused by excessive strain through a large quantity of stiff batter, then the nylon worm gear will shred. This essentially protects the motor, and the rest of the gears, from jamming or shredding when the machine can’t handle the heavy workload.

While in theory, this makes sense, in practice, many bakers found this gear shredded prematurely, leading to frequent gear replacements.  In 1998 a new nylon gear reinforced with Kevlar fibers was introduced to their classic line of mixers. This made the worm gear more durable, yet still enabled it to shred if the motor was overloaded. 

Despite the updated design of the worm gear, some KitchenAid users still find that the worm gear becomes worn down fairly quickly. It’s one of the biggest factors that impact KitchenAid’s life expectancy.   

If you notice your KitchenAid starts to become less effective, it’s a sign that it might be time to check your worm gear. The good news is that you can pick up a replacement worm gear pretty cheap, (just be sure to get an O.E.M. authorized one) and replace the gear yourself. 

If you want to learn how to replace this gear yourself, here’s a helpful video.

Which KitchenAid mixers have metal gears?

Today almost every KitchenAid stand mixer has steel gears. In fact, it’s only the KitchenAid Classic and Artisan 5 Series that use nylon worm gear. The Artisan Mini and every KitchenAid bowl lift mixer now have all-metal gearing.

That said, if you had your heart set on a new Classic or Artisan 5 Series model, I don’t think you should let this put you off. This Nylon gear (reinforced with Kevlar) is put there to protect the smaller motors in these mixers, and prevent the motor for being overloaded and completely destroying your motor. Replacement worm gears are widely available and can be changed yourself, or by a professional repair shop, depending on how confident you feel taking your prized mixer apart.

It’s also worth bearing in mind that the worm gear is the only plastic gear in the Classic and Artisan 5 Series. Other important parts of the mixer gearing (like the gear drive, planetary ring, and pinion gear) are still made from metal, just like the other models.

Something else to remember is that the KitchenAid metal gears aren’t exactly impervious to damage either. After seeing their fair share of action, these gears can become over time too (take another look at the photo above!). That said, they should be substantially more durable than the nylon worm gear.