How Mechanical Keyboard Switches Are Made

After having both collected mechanical keyboard switches for many years, I can say without a doubt that they are some of the most underappreciated components of the entire keyboard hobby. Unlike previous articles where I lead with that as a precursor to discuss the wide range of switches out there or the unique mechanisms being crammed into switches these days, I'm saying this here because they are actually incredibly complicated, multi-part components that have a not insignificant amount of effort required to manufacture them.

For all of the discussions we see everywhere about keyboard kit and keycap quality control and defects, the fact that we basically don't see any complaints about defective or unusable switches is pretty close to miraculous when you realize what all goes into putting these switches together.

And yet, I have realized over the years that most people don't even know how MX style switches come together, let alone why the sheer lack of defects we see are so miraculous. In order to change that for you all here today, I figured that it would be worthwhile to run through the steps of how all of your favorite keyboard switches actually got produced!

Step 1 – Injection Molding Parts

All of the plastic components of keyboard switches are all first made in various different batches via a process known as injection molding. Injection molding is a manufacturing process which takes plastic pellets or chips of specific materials like POM, nylon, or polycarbonate, melts them down until they are soft and then forces them under great pressure into tight cavities shaped to whatever specifications you want.

In order to withstand the high pressures and temperatures required of such a process, these cavities and part shapes are machined out of thick metal block known as "molds" and often contain not just one part but dozens of parts all connected together by channels that feed back to one point. These channels, which are referred to as either 'sprues' or 'runners' all go back to a single point where the machine will inject the plastic and effectively allow manufacturers to produce dozens of parts with just one cycle of the machine – something which is crucial for making switch parts cheaply.

It also is definitely worth noting not just that switches require three different sets of molds in their production, for both housing and stem designs, but also that each of these molds are quite expensive to produce and cost well into the tens of thousands of dollars to design and machine. After a complete cycle of stems or housings is injected and then cooled to a solid state within these molds, the molds are opened and the parts with attached sprues/runners collected for the next stage of processing.

Step 2 – Quality Control Check and Part Cleanup

Once the injection molded switch stems and housings have made their way out of the fancy and high tech injection molding process, they're surprisingly checked for quality control and spruced up by incredibly low tech means – individual manual labor. While each factory may carry out this step differently, it is often that the injection molded parts are manually snipped away from their sprues/runners, separated into different piles, and cleaned if there is any residual plastic or processing gunk that shouldn't be on the parts at all.

Much like how Gundams or other model figurines have parts that come attached with a webbing of supportive plastic, these workers have to remove the stems and housings and inspect them for defects, lack of complete molding, and then sort them into usable buckets if they're inspecting more than one at a time. As can be seen below in Figure 3, this worker has already removed the brown, tactile stems from their sprues/runners which are tossed in the bucket to the right and is in the process of checking and evaluating each and every one of the stems.

It is also worth noting that some companies can and will actually melt down the 'waste' sprues being collected here for future injection molding runs in order to save on raw material costs.

Step 3 – Metal Leaf Preparation

While the stems and housings of switches are in the process of being molded, inspected, and separated for use in the final processing step of the switches, both the large and small leaves of traditional MX style switches go through their own parallel process to get them prepared. Rather than coming in bags of individuals parts like how stems are transported after they are molded, the leaves of keyboard switches come already present on a giant, narrow roll of thin metal sheeting that are transported via large blue holding rolls as seen above in Figure 4.

After all, switches leaves are just thin sheets of metal on their own cut into specific shapes and bent in the case of the large leaf. Either at the factory where the switches are being put together or at the companies which make the large rolls of metal sheets that are used to make the leaves, the actual shapes of the leaves are cut out via large stamp presses that keeps them just connected enough to the long metal strip to let them be able to be fed into the assembly machines in a belted fashion without falling apart.

These belts of both large leaves and small leaves are then fed directly into the all-in-one assembly machines discussed in the next step which punch then out of their metal strips and directly inject them into the bottom housings where they remain. As can be seen in the images below, both the large and small leaves are stamped on different rolls of leaf metal and are fed into the machines via different paths.

Step 4 – Part by Part Assembly

In the final manufacturing step of keyboard switches, all of the parts that are produced and prepared through the first three steps above are combined into a single switch via an assembly machine like the one shown above. These parts all come together through a series of sorters, organizers, and mechanical setups that basically line up each of the parts in a series of machine arms that put them together in the same step wise fashion that you'd reconstruct switches from parts on your own.

Bottom housings are fed via a winding circular sorter until they're oriented in holders on the assembly line that they are moved through the process on. Small and then large metal leaves are sequentially stamped out of their bands, injected into the housing, and then bent into proper shape via specially programmed arms. Next springs, stems, and then factory lubing are added to the bottom housings in differing orders depending on the factory that is manufacturing them. (Springs and stems, of course, are sorted into the machine through the same circular organizers as those of the bottom housings)

And then finally, the top housings are placed onto the switch and pressed down firmly until they click into place and result in a complete, finished keyboard switch. While this process seems rather simple in a piece-by-piece step wise fashion, the fact that these machines are highly automated and engineered means that this process can be carried out super quickly and result in thousands of switches per hour!

Appreciating the Complexity of Switch Manufacturing

To think that the millions upon millions of different switches are produced in this fashion ever year and yet we as a community see so few manufacturing defects or errors is honestly a bit crazy to sit and think about. Keycaps and keyboards are sure difficult to manufacture in their own rights, but running through this really does give me a much deeper appreciation for all of the detail and efforts that go into switches.

Hopefully you too will have gained a deeper appreciation for switches and their complexities after learning how they come together. If you want to gain an even deeper appreciation for switches and learn some more things that you didn't know about them, consider some of my other articles here on Kinetic Labs such as 'Switch Materials Are a Bit Complicated' and 'The Four Common Types of MX Switch Mechanisms'!