Sewing Machine Feed Mechanism

Feed mechanisms is the basic motion of needles, loopers and bobbins, the material being sewn must move so that each cycle of needle motion involves a different part of the material.
This motion is known as feed mechanism.

Sewing machine feed mechanism is that which is used for moving the fabrics being stitched from one stitch position to the next. It is one of the most important parts of the sewing machine.

Feed Mechanism

Function:

The following are the function of a sewing machine, which is totally depends on the feed mechanism.

Proper seam appearance,
Proper stitching as required,
Controlling of SPI ( Stitch per inch),
Moving forward and backward of sewn fabric,
Sometimes crease effect is formed according to the design.

There are so many types of feed mechanisms are available according to the desired function and machine. But, common three parts are must whatever the type of feed mechanism is.
The following are the three parts of a sewing machine feed mechanism, which are pointed out in the below:

Different Parts of Sewing Machine Feed Mechanism:

Throat plate or needle plate or feed plate,
Feed dog,
Pressure foot.

1. Throat plate or needle plate or feed plate:

The part of the bed of the sewing machine which has opening for the needle and for feed dog penetrations and which provides localized support to the material. Here, the opening varies in size and shape which is depending on the sewing requirements. This is made of steel and its surface is very smooth. Due to the smooth surface fabrics can be feed easily. It is also called needle plate or feed plate.

Throat plate or needle plate or feed plate

It has one or more slots through which feed dog can move forward and backward. It has a hole through which needle can move up and down with the thread. Size of this hole should not exceed more than 30% of needle size.

2. Feed dog:

A toothed element which acts on the surface of material is being sewn to move it in a controlled way during stitching. The actions in normally on the lower surface of the material but mechanisms which acts on the upper surfaces are also in use. For most of the time, the operative motion is forwards but in specific cases the motion is reversed. It is the most important part of the feed mechanism. The main function of this part is to move sewn fabric after making individual stitch as predetermined length.

Feed dog

To prevent the slippage of fabric, the upper parts of the feed do are made toothed. The movement of the feed dog is lateral. Feed dog moves backward and comes upward through the slot of the throat plate which contacting with lower surface of the fabric and moves the fabric forward a step and then descends from the fabric and moves down again below the throat plate. In this way, its lateral movement is completed.

3. Pressure foot:

This is an element which is used to constrain the movement of the material during stitch formation by applying to it an adjustable downward pressure. Pressure foot works in conjunctions with the throat plate and feed dog to achieve controlled movement of the material and correct stitch formation.

Pressure foot

Different designs of pressure foot are in use. The most common have a solid or hinged surface which controls the material. It is used to give an adjustable downward pressure on the fabric with spring pressure. So that fabric cannot move up and down with needle. Lower surface of the pressure foot is very smooth to prevent less friction between fabric and pressure foot.