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The needle-bed of a knitting machine is made up by the needles. As we said before, the needles can be all fixed on the same needle bar or can be driven individually in a grooved plate, according to the type of knitting machine.
All knitting machines can be equipped with one or two needle-beds, according to the model.
The needle-bed of a knitting machine can be flat or circular. It is made up of a steel body provided with grooves where the needles with hook and butt turned upward slide. The milled grooves guide the needles during the knitting process.
The needle-bed is characterised by two elements:
- the operating width
- the gauge
The operating width is the maximum working area and varies according to the type of machine for example in a flat-bed machine the operating width is the distance between the first and the last needle while in circular knitting machines the operating width is the needle-bed diameter.
The gauge is the population of needles on a certain length of bed. The English Gauge is the number of needles included in an English inch, that is to say how many are included in 2.54 needle-bed centimetres.
From a conceptual point of view, the English inch is measured from the centerline of a needle but usually it is the distance corresponding to 1 inch, measured from one side of the needle to the same side of another needle within 1 inch. For example: if we start from the right side of the first needle we will have to reach the right side of the last needle.
The gauge refers always and only to one of the two needle-beds.
The English gauge is indicated with a capital E and is used for all the weft knitting machines and warp knitting frames.
There are also other types of gauges used for other machines and specifically:
- the English Raschel Gauge for Raschel looms is indicated with the capital letters “ER” and refers to the number of needles included in 2 inches, that is to say in 5.08 centimetres;
- the GG Gauge is indicated with the capital letters GG and refers to the number of needles included in 1.5 inches, that is to say in 3.81 centimetres. This gauge is used for flat-bed full-fashioned machines and for English circular machines.
- French Gauge is indicated with the Gros symbol and refers to the number of needles included in 1.5 French inches, that is to say in 4.16 centimetres. It is used for loopwheel circular machines.