A Basic Intro to Technical Knitting
In a previous post about Everyday Knits and How They're Made, I mentioned Technical Knitting and promised that I would talk more about it in a future post.
Last week, I ventured down to Malibu to visit the state of the art knitting facility that is home to Fab Designs' knitting experts Bruce and Connie Huffa. They were gracious enough to invite clients from start-ups, major shoe companies, to Fortune 500 behemoths for a knitting summit.
I won't try to do what they did in three days in one post, but if you or your company is interested in manufacturing technical knit products, you'll save yourself and the experts a headache by knowing what you're getting into.
Most fashion designers and even textiles designers do not know the technical details about fibers and yarns. To make a high-quality technical knit product that does exactly what you want it to, learning is essential. The education system in the United States is set up such that we are used to sending products and swatches overseas and having them reverse engineered and replicated. It has been economically more efficient to develop products this way. However, it means relinquishing control and IP to the vendor.
There are a few places where this kind of knowledge is still being shared. North Carolina has always been the textiles epicenter of America. Manufacturing Solutions Center (MSC) provides training programs for technical jobs in textiles and knitting. NC State has a textiles engineering program. Check out Resources for more info.
Fiber Type is the first consideration to make. Are you looking for a natural fiber or a synthetic fiber? You should consider your customer needs and the advantages of each fiber-type first. Do you have performance requirements? Natural fibers will burn, synthetics will melt. Synthetics have a higher resistance to abrasion, but lower breathability. From a sustainability perspective, natural fibers are biodegradable but are highly energy consumptive. (Cotton for example.) Many synthetic fibers are petroleum-based, cannot be biodegraded, but can be reclaimed.
There are an infinite amount of combinations of fibers and physical configurations that can make up a yarn. Even achieving a specific characteristic like "soft" can use a different techniques and a huge array of fibers and finishing processes.
Yarns can be made from a large array of fibers. Cotton for instance can be open end or ring spun. It can be mercerized, sanforized, gassed. Spandex is sticky if it isn't covered with another fiber. You can cover spandex/lycra with a double cover, a single cover. You can also air cover spandex. You can air cover yarns by
Single cover vs double cover - describe filament yarns (like spandex) which are covered with a softer yarn. A single cover has a single yarn which coils around the core filament. A double cover has two yarns which coil in opposite directions around the core filament.
Air covered yarns - are yarns that are shot by a jet of air that intermingles the strands of fiber.
This is just skimming the surface of yarn types. If you want to learn more about fiber and yarns, you should take the Hosiery 101/102 class at Manufacturing Solutions Center or learn more online at FabricLink. If you're interested in the engineering processes behind some of these yarns, check out Textiles Study Center.
You'll be annoyed to hear that different fiber types have different units of measure. There is wool run, worsted, cotton count, denier, decitex... If you are trying to do these conversions, check out the Online Yarn Calculator from Leg Source.
The yarn used in the textile in the image above is a single covered elastic. The elastic is the first number (top line): 40 denier. It is covered with 2 ends (middle line) of 40/34. The 40/34 describes 40 denier with 34 filaments of a synthetic fiber. The filament count can have a lot to do with softness. Generally speaking, the higher the filament count, the softer the yarn.
Machine knitting gauges generally range from 3 to 24. Gauge (gg) refers to stitches per inch. The lower gauge has larger stitches, that higher gauge has smaller stitches. The way that gauge is described and used hand knitting, home machine knitting, and industrial machine knitting are all a little bit different. Wikipedia explains some of this. Each knitting machine is set up for a specific gauge. Which gauge you will need depends on the type of product you are trying to make.
Some stitch types are not compatible with others. Some take much longer to knit than others. For example, a pointelle, which requires a lot of transferring to achieve, takes a lot longer to knit than a standard jersey. Learn more about different stitch types (knit constructions) at Fabric Link.
Possibility is endless when it comes to knitting 3D shapes. Products from automotive and industrial upholstery to shoes to sweaters can all be made on a flatbed knitting machine. However, do not assume that this process is anything like 3D printing. It takes much more development and know-how than many other soft good products because you're building the entire product from fiber and yarn to 3D part. It will not magically program the machine to do what you want, especially if you cannot describe it. Although, Disney Research has been working on a compiler for high-level primitives to knit 3D shapes, they are not able to accommodate for different stitch types.