01 Physical indicators of shaping control
1. The door width can be directly adjusted during production Adjust on the setting machine. The adjustable door width on the shaping machine is in centimeters, but the company’s order requirements generally require door widths in inches. Therefore, during the production process, inches must be converted into centimeters before adjustment can be made. Conversion formula: 1 inch = 2.54 centimeters.
2. Gram weight Generally, gram weight is controlled by adjusting overfeeding. Under the condition that the other tensions remain unchanged, within a certain range, the greater the overfeed, the heavier the gram weight, and the smaller the overfeed, the lighter the gram weight.
3. Cycle cycle is closely related to the gram weight, which refers to the repeated size of the pattern from the starting point to the end point. Its control method is the same as that of gram weight. Typically, cycling is controlled by adjusting overfeed. When the remaining tension remains unchanged, within a certain range, the larger the overfeed is, the shorter the cycle will be, and the smaller the overfeed will be, the longer the cycle will be.
4. Shrinkage Shrinkage is one of the most important physical indicators that need to be controlled when shaping. The shrinkage must be even and reasonable to be OK. For styling, shrinkage is mainly controlled through resin or pre-shaping.
For pure cotton fabrics, resin is generally used to control shrinkage. When the resin can fully react, the greater the amount of resin, the better the shrinkage, but the problem that arises is that the strength decreases more. Therefore, the amount of resin is subject to certain restrictions. Under normal circumstances, B/F strength is >85PSI, the test method is TUMBLEDRY fabric type, and the resin dosage is 50G/L. Generally, a formula with a resin dosage of 50G/L is regarded as a complete material. For pure cotton double-sided fabrics that only undergo ordinary finishing, the resin dosage of 80G/L is regarded as the entire material. Test methods for LINEDRY, HANGDRY, and FLATDRY generally reduce resin production to save costs.
5. Distortion Due to the twisting of the yarn, the yarn has a certain tendency to twist back after being woven into fabric, forming distortion. The tendency to twist is more pronounced in single-sided fabrics.
The size of the distortion is related to the twist of the yarn itself, the fabric structure and the knitting process. Twist is generally controlled by oblique shaping or step-by-step shaping. In many cases, a combination of the two methods is also used. However, for resin-made fabrics, the only way to improve distortion is through diagonal shaping; for resin-coated fabrics, step-by-step shaping can be used to improve distortion.
When the amount of resin cannot be too large due to strength reasons or the slanting of the fabric itself is too large and exceeds the adjustable range of the setting machine, and the step-by-step setting cannot achieve the required distortion, the method of combining oblique setting and step-by-step setting can be used to improve it. distortion.
6. Strong strength is a physical indicator that cannot be repaired, so it must be carefully controlled during the production process. The strength is related to the quality of raw materials, cloth structure, knitting process, degree of resin reaction and pre-treatment process. For shaping, the damage to strong force should be minimized while ensuring physical indicators such as shrinkage, pilling, and distortion. When these indicators cannot be taken into consideration at the same time, priority should be given to maintaining strength.
7. Formaldehyde content Generally, high formaldehyde content is caused by incomplete resin reaction. Generally, the formaldehyde content requirement for adult clothing is <75ppm. For some orders that make children's clothing and underwear, the formaldehyde content is required to be <20ppm. As long as the resin reaction is sufficient, the formaldehyde content of adult clothing will generally meet the requirements. For demanding children's clothing and underwear items, try to avoid resin finishing. If it is necessary to pass the resin in order to achieve other physical indicators, you can only arrange to backwash the formaldehyde after passing the resin, and then wet-set it.
8. PH value Customers require the PH value of the cloth to be weakly acidic or neutral. Generally, the PH value of the finished product cannot exceed 8. NIKE, TOMMY and most domestic customers have strict requirements on PH value: light white PH range: 4.5-6.5. Therefore, all fabrics produced by these customers must pay attention to strict control of PH value. The pH value is first adjusted by HAC in the dye vat.
02 Common defects in styling and customer service methods
1. Uneven stitches (refers to uneven needle widths on the edge of the fabric, Width >10CM) Causes: 1. The needle plate screws are loose and the needle plate is skewed, 2. The edge detector is malfunctioning, and the screw wear correction time lags behind, 3. The needle plate chain is inflexible
Overcoming methods: 1. Adjust the position of the needle plate, tighten the screws, repair the edge detector to make it flexible and correct the lag, 2. Strengthen the cleaning and lubrication between the chain pin and the sleeve, the sleeve and the ball
2. Hole in the needle eye Causes: 1. The expansion is too large, which damages the fabric edge fibers. 2. The expansion ratio of the needle chain track plate is out of balance. 3. There are bent needles on the needle plate and the needles are broken
Overcoming methods: 1 .Adjust the stretch to a reasonable level, do not stretch or pull hard 2. Correct the stretch ratio of the track plate 3. Replace the needle plate with bent or broken needles
3. Reasons for the door width not meeting the process requirements: 1. The door width pointer does not match the actual door width. 2. The amplitude modulation screw is damaged, causing the pointer to not match the actual door width. 3. The amplitude modulation clutches in the front, middle and rear positions are not tightly matched, causing the door width to automatically move backward, making the door width inaccurate.
Measures to overcome: 1. Correct the door width pointer to the standard door width 2. Check and repair the amplitude modulation screw 3. Check and repair the amplitude modulation clutch
4. Causes of latitudinal skew: 1. Running track The number of needle clips on the two sides is different, which makes the weft yarn on both sides of the fabric inconsistent. 2. The needle clip chain runs on the sleeve, and the pin wear is different, which makes the actual running length of the two sides different. 3. The speed of the brush active roller is different when overfeeding. 4. The pressure on both sides of the overfeed roller is uneven or the structure is uneven, resulting in uneven warp tension on both sides of the fabric.
Measures to overcome: 1. The number of needle clips on both sides of the track must be consistent 2. Replace them in time if there is any wear.�� Sleeve, pin 3. The speed of the brush and overfeed roller must be controlled consistently. The motor must be replaced if necessary. The dry humidity on both sides must be consistent before the fabric is set.
5. Needle plate mark (referring to the appearance after dyeing) Needle plate bar shape) Reasons: 1. The unevenness between the needle plates 2. The needle clip chain cannot rotate flexibly or the chain is too loose 3. The upper needle brush presses the fabric too tightly, making the fabric close to the bottom of the needle plate, and the hot air circulates Not smooth, there is a temperature difference on both sides
To overcome the problem: 1. Flatten the uneven needle plate and needle clip with mica to make it a straight and horizontal line, keep the chain roller lubricated, rotate flexibly, and have appropriate tightness to make the needle The plate convergence turns into a straight line 3. Adjust the height position of the brush so that it is in contact with the short needle 4. Preheat the needle plate chain to the process temperature before loading the cloth and driving
6. Moon edge or ruffle edge Reasons: 1. Part of the needle plate has broken needles or wear. 2. The upper needle brush is worn or grooved. 3. The adjacent needle plates are uneven, so that the lower part of the needle plate does not penetrate the needle deeply into the fabric edge. When the stretch tension is applied, Sliding out the needle plate
To overcome the problem: 1. Replace the broken needle or damaged needle plate 2. Replace the worn upper needle brush 3. Correct the needle plate so that the upper and lower heights are level
03 What should I do when curling the edges?
1. When stenter shaping
In the rolling groove of the shaping machine, soft finishing can meet the customer’s requirements for the cloth, and make it in the guide The cloth wheel is not easy to scratch, and the tenter setting makes the fabric surface flat and stable in size, which can eliminate wrinkles and creases formed during the dyeing and finishing process. At the same time, the setting process conditions need to be strictly controlled during setting.
The setting temperature should be determined according to the elastic shrinkage and thickness of the fabric. If the temperature is too high, the strength will decrease, the elasticity will decrease, and the fabric may change color. If the setting temperature is too low, the fabric will curl easily, the width will be unstable, and the shrinkage rate will be large;
The setting speed mainly depends on the length of the setting area and the setting temperature. If the speed is too high, the setting temperature will be too low. Quick setting has no effect, fine wrinkles are difficult to solve during the dyeing and finishing process, and the fabric turns yellow and its elasticity decreases due to slow speed, especially under high temperature conditions.
For stereotyped overfeeding, after determining the fabric width, select the appropriate overfeeding amount and tension, which affects the weight, elasticity, and wrinkles of the fabric surface. , such as the fabric tension is small, the overfeed is large, and the cloth surface is uneven, it is difficult to eliminate the fine wrinkles produced by the fabric during the dyeing process. The tension is large, the overfeed is small, and it will cause curling during heat setting.
2. Styling conditions
When pre-styling cotton and spandex knitted fabrics, different manufacturers should be taken into consideration The spandex yarns produced are adapted to different setting temperatures. For example, the spandex produced by DuPont can withstand a setting temperature of 190°C, while the spandex produced by some setting machines has a setting temperature as low as about 180°C.
Generally, the content of spandex is less than 5%. Knitted fabrics with not serious curling when cutting the width can be directly dyed in open width after pre-shaping. If the content is greater than 5%, the open edge will affect the dyeing of knitted fabrics. After the object is pre-shaped, it must be sewn into a tube shape before dyeing, otherwise the dyeing problem caused by curling cannot be overcome.
When dyeing knitted fabrics, choosing the appropriate cloth speed and nozzle pressure can achieve better dyeing results. The cycle time is preferably 2 to 3 minutes. The calculation formula for vehicle speed is: cloth speed = Cloth loop length/cloth cycle time.