For industrial sewing machines, a thorough understanding of the traction (tension) of the feed mechanism is crucial. A suitable feed mechanism is essential to achieve the preset stitch length and minimize fabric drift and wrinkling. Sometimes, a looser fit is required with thicker or smoother fabrics, making it even more important to ensure proper fabric feeding throughout the entire process. Several feed mechanisms are currently available on the market.
I. Bottom Feed Mechanism
Bottom feed is the most basic, classic, and widely used feeding method.
#BOTTOM FEED WITH ROLLER
Structure and Working Principle: The core components of this mechanism are the feed dog located below the needle plate and the presser foot, which provides pressure. During operation, the feed dog moves along an elliptical or rectangular trajectory. This trajectory can be broken down into four stages:
Rising: After the needle pierces the fabric, the feed dog rises from the needle plate groove and contacts the back of the fabric.
Feeding: The feed dog, pressing against the fabric, moves forward one stitch length with the assistance of the presser foot. This is the crucial feeding stage.
Descent: After feeding is complete, the feed dog descends, disengaging from the fabric.
Retraction: The feed dog retracts to its starting position below the needle plate, preparing for the next cycle.
Features and Applications: Bottom feed has a simple, reliable, and low-cost structure, suitable for most conventional sewing. However, it is prone to layer shifting (commonly known as uneven feed) when sewing multi-layered or elastic fabrics because only the bottom layer is directly driven by the feed dogs.
II. Needle Feed Mechanism To solve the problem of multi-layer shifting during bottom feeding, the needle feed mechanism was developed.
Structure and Working Principle: This mechanism is characterized by the needle itself participating in the feeding motion. As the feed dogs push the fabric forward, the needle, after piercing the fabric, swings forward a short distance synchronously with the feed dogs before rising. In this way, the needle applies a forward force from the upper layer of the fabric, working in synergy with the lower layer of the feed dogs.
Features and Applications: Needle feed significantly improves the sewing quality of multi-layered fabrics (such as thick canvas and leather patchwork), effectively preventing layer shifting and ensuring neat and consistent stitches. It is widely used in sewing machines for bags, shoes, hats, sofas, and heavy-duty industrial fabrics.
III. Synchronous Feed Mechanism Synchronous feed is an enhanced version of needle feed, designed to provide the most balanced feed force.
#COMPOUND FEED WITH WALKING FOOT
Structure and Working Principle: In this mechanism, the feed dogs and needles (usually via a slide or a specific feed frame) are rigidly connected or linked, moving at the same speed and distance. They move together as a single unit, "clamping" the fabric during the feeding phase.
Features and Applications: Synchronous feeding provides excellent feed control, virtually eliminating layer shifting. It is particularly suitable for sewing fabrics prone to slippage (such as nylon, tarpaulin), multi-layered fabrics, and applications requiring precise pattern matching (such as quilting). This is one of the hallmark technologies in high-precision sewing.
IV. Differential Feed Mechanism
Differential feeding is primarily used for handling elastic fabrics or sewing requiring special effects.
Structure and Working Principle: This mechanism has two independent sets of feed dogs-a front feed dog and a rear feed dog. The feed amount (stitch pitch) of each set of dogs can be adjusted independently. When the feed amount of the back teeth is greater than that of the front teeth, a "shrinking" effect is produced, used to prevent stitches from tearing when sewing elastic fabrics; when the feed amount of the front teeth is greater than that of the back teeth, a "stretching" effect is produced, used to create decorative stitches such as pleats and wrinkles.
Features and Applications: Differential feed is an essential function for knitted garments, sportswear, underwear, and some decorative sewing. It gives sewing machines a powerful ability to handle the stretch of different fabrics.
V. Upper Feed Mechanism
#TOP AND BOTTOM FEED
When the fabric surface has special characteristics (such as napped or coated fabrics) that cannot withstand the scratching of the feed dogs, upper feed becomes the ideal choice.
Structure and Working Principle: Upper feed is also called a "walking presser foot." Its presser foot itself is an independent drive component that can reciprocate like the feed dogs. During the feeding phase, the presser foot descends and clamps the fabric, advancing synchronously with the lower feed dog; then the presser foot rises and returns to its original position.
Features and Applications: Upper feed achieves true synchronous up-and-down drive, avoiding the feed dogs leaving teeth marks on the back of the fabric and protecting the fabric's appearance. Widely used in leather, artificial leather, suede fabrics, and quilting operations.
VI. Integrated and Specialized Feeding Modern high-end industrial sewing machines often combine multiple feeding methods to form integrated feeding, such as a combination of "bottom feeding + needle feeding + top feeding," to handle the most complex sewing conditions.
In addition, there are some specialized feeding mechanisms, such as:
Roller feeding: Used in embroidery machines or for specific materials, this motor-driven roller feeding provides very smooth operation.
Clamping plate feeding: Used for sewing extremely thick or hard materials.
If your want to learn more about or plan to purchase high quality industrial sewing machine, please feel free to contact KINGMAX.
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