Have you ever thought about the process that goes into making those sleek, tech-loaded running shoes you strap on every day?
It’s not something we need to know in order to make the most of our shoes, but it’s an interesting process and can help you appreciate your gear a little more!
So how are running shoes made? Here’s a brief overview of how those comfy, designer running shoes come to be.
How Are Running Shoes Made?
The process of making running shoes is something called a cold cement construction process. It’s a way of creating high-quality products out of top materials, by using a low temperature to bond the shoes together.
In order to really understand the process, we should learn a little about the anatomy of the running shoe.
What Are the Parts of a Running Shoe?
There are really only two parts of a running shoe: the upper and the sole. Let’s dig deeper into each one!
What is the Sole Made Out Of?
The sole of a running shoe consists of three layers: the insole, the outsole, and the midsole.
Different manufacturers use different materials to make the parts of their soles. EVA, polyurethane, gel, other foams, and even liquid components are common in midsoles. Insoles are usually made of foam with a fabric covering.
Outsoles usually consist of some kind of rubber, although there are those that are made of polyurethane.
The outsole and midsole are usually fused together. Insoles are often removable, to make space for custom orthotics if needed.
What Is the Upper Made Out Of?
Most running shoe brands use mesh on their upper. It’s light and breathable, perfect for exercise. Some use leather, which is more supportive but less ventilated, even with perforations. Others use knit polyester, which contours nicely to the foot.
Many pairs of running shoes have synthetic overlays on their uppers. These are usually made from polyurethane or leather, depending on the shoe.
The Manufacturing Process:
There’s a very similar process that goes on in every factory. Whichever manufacturer creates your shoes, chances are they’re being made practically the same way.
Getting the Fabric
The fabric is usually bought ready-prepared. They come in large rolls or synthetic mesh, other textiles, or leather.
The shoe factory will order these in bulk, and they’re shipped to the factory already dyed in their specific colors.
Shoe Shapes Die-Cut
Once the factory has received their fabric, they’ll cut the shoe shapes out of the rolls of fabric using a die-cutter. These are done cookie-cutter style, so there’s very little chance of anything going wrong.
Assembling the Upper and Insole
In the factory, the various cutouts that will form the upper of the shoe are bonded together. These include the vamp, the tongue, the throat (the part with the lacing holes), any reinforcements or overlays, the heel collar, and any logos that need to be added.
This bonding process may be by stitching, or by “cementing”, which is just a fancy way of saying they’re glued together. It’s during this step that the lace holes will be punched out of the upper.
The upper doesn’t really look like a shoe at this point. Although the pieces are connected, there’s nothing keeping the shoe together in a foot-like structure.
Now, the insole is attached to the sides of the upper if (and only if) it’s a non-removable insole. This gets integrated into the entire upper and can’t be taken out later.
After this, there may be stiffer sections added to the toe and heel for reinforcement.
Fitting It to a Last
Once the upper reaches that point, it needs to be fitted to a shoe last. A last is a mold that will create the final shape of the shoe. This is what gives it an actual shoe-like shape, rather than just floppy material.
The shoe last is the deciding factor when it comes to things like the shape of toe boxes, the width of the heel, or and the heel-to-toe drop. It plays a huge role in the final ergonomic design of the footwear.
The upper is heated to make it easier to stretch over this mold, which is done by an automatic lasting machine. Once stretched and in place, the molded upper is glued (or cemented) to an insole board.
The Midsole & Outsole Are Added
With the plastic lasting mold still inside the shoe, the midsole and outsole are added to the footwear. These are also pre-cut for the shape and size of the shoe.
Outsole wedges or rubber layers and midsole chunks come separately. The first step here is to cement the outsole and midsole together in perfect alignment.
Once this has been done and is dry, the completed outsole/midsole unit is then aligned with the upper, which is still on the last. In most cases, these are then heated so the existing cement (or glue) melts and can be reused to attach the two.
That way, the manufacturing process isn’t adding any extra glue to the shoe, but rather using a single application where possible to save weight.
Often, the shoe will then be put through some form of rapid cooling. This will cause the upper to contract around the last and settle into its proper, final shape.
Now it’s time to remove the last. Because the upper has been placed tightly around it, this isn’t really something that can happen by hand, so an automatic de-lasting machine is usually how it’s done.
These machines start by securing the last upside-down on a spike. The outsole of the shoe is facing upwards at this stage.
An arm of the machine grabs the shoe by the heel, and simply flicks it off the last, with power that we can’t quite get with just our hands. It leaves no damage, and you’re left with a beautiful, well-shaped running shoe!
Adding An Insert
If the insole hasn’t already been added at this stage, it’s the only thing now missing from the shoe. This is the point at which it will be added.
Most manufacturers purposefully add it later on and not in the midst of the shoe creation process, so that it can be easily removed to make way for custom insoles.
Quality Control Inspection
At this stage, the shoe is ready for a quality control inspection. Here it will be closely checked for any sign of manufacturing defects.
These could be things like loose threads from the material on the upper, places where parts may not have bonded together properly, or any damage to the materials that wasn’t noticed earlier.
Shoes that don’t pass the QC inspection may end up going to factory shops and sold for cheaper prices, or in some cases they may be recycled and their materials used again in the full shoe-making process.
Those that do pass the quality control inspection are then sent to be cleaned. During the manufacturing process, dust and grime can settle on the various parts of the shoe, leaving it looking like a pair of old, used footwear!
The cleaning process gets rid of all that dirt and the shoes come out looking like a squeaky clean, brand new pair of running shoes. This cleaning process is safe and doesn’t do any damage to the newly-constructed shoe
The last step of the entire process is packaging the shoes in their relevant pairs. These then get sent off to various stores and warehouses so they can be sold to runners like ourselves!