Industrial knobs offer a convenient way to control machinery. Once installed, you can turn them to tighten or adjust a piece of machinery. When shopping for an industrial knob, however, you’ll need to consider the insert type. While all industrial knobs have a gripping surface, they are available in different insert types.
What Are Inserts?
An insert is a separate piece — typically made of metal — that’s incorporated or molded into an industrial knob during production. It serves two purposes: to provide the knob with strength and maximum torque, and to provide the necessary threading for installation.
Without an insert, industrial knobs may lack the strength for full-strength turning. You may inadvertently break or damage them when turning them at full force. At the same time, there typically won’t be threading on the knob to install it.
Internal vs External Threads
Inserts are available with internal threads and with external threads. Internal threads consist of a hole with helical ridges around the perimeter. External threads, on the other hand, consist of a bolt-like threaded rod.
You can install a knob with internal or external threads, assuming the machinery has the opposite thread type. If you’re using a knob with internal threads, the machinery needs to have external threads. If you’re using a knob with external threads, the machinery needs to have internal threads. You can’t install a knob with a machinery if they feature the same thread type.
What Are Inserts Made Of?
Inserts are typically made of metal. One of the most common materials used in the construction of knob inserts is zinc-plated steel. It’s strong, long-lasting and offers excellent protection from rust and corrosion.
Zinc-plated steel consists of premium stainless steel with a thin outer layer of zinc. The zinc is applied using a process such as electroplating or hot-dip galvanization. With electroplating, an electrical current is applied to a solution, which causes zinc particles to stick to the surface of the steel. Hot-dip galvanization, in comparison, involves submerging the steel in a bath of molten zinc.
What Are Molded Insert Threads?
While most knobs feature a metal insert that’s incorporated into the base during production, some feature molded insert threads.
Also known as plastic threads, molded insert threads are exactly what they sound like: plastic threads that are molded into the plastic itself.
Molded insert threads aren’t as strong as zinc-plated steel threads. Therefore, if you’re looking for a knob that can handle high torque, you may want to avoid them. For low-torque applications, though, molded insert threads offer a cost-effective alternative to traditional metal inserts.