inspection procedures for quality assurance in cutting
Post on 21-Apr-2015
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Procedures Practiced for Quality Control and Assurance (Cutting) Process of Inspection, Types of Defects and their possible solutions, (Marker making, spreading, cutting, bundling , ticketing quality parameters and formats ) Quality Specs.
Introduction In-Process Inspection In-process inspection means the inspection of parts before they are assembled into a complete product. In apparel manufacturing, this means inspection at various points in the entire manufacturing process from spreading to pressing / finishing The idea behind the in process inspection is to inspect or check the quality of component parts close to the manufacturing a possible and thereby identify the source of quality problems as early in the manufacturing process as possible.
Contd.. This type of inspection can be performed by either quality control inspectors or individual operators themselves after they perform their respective operations. This will minimize the need for later repairs and rework. Each production operation performed correctly makes for a smooth running plant with low operating costs. Poor quality at any stage in production compounds itself and can be expected to increase total cost. In process inspection is also called as during production or du-pro inspection
In-process Inspection - Advantages Reduction of major surprises from the customers due to bad quality. Decrease in labor costs due to decrease in repair rates. These advantages are generally derived from the fact that due to in-process inspection
The operators (workers) and supervisors are constantly reminded that the company has a specific quality level to meet, just by the very presence of the inspectors in their section on a daily basis. Because each worker realize that his/her work is subjected to being inspected at any time throughout the day the quality of work produced by workers will improve The data obtained can be effectively analyzed and utilized by the production supervisors and plant manager in correcting problems or improving quality.
The day is long past when apparel manufacturers can depend solely on 100% final inspection at the end of a production line. The quality cannot be inspected into a garment after it has been made; instead, quality should be manufactured into a garment at every step and checked repeatedly during production.
In-Process inspection - Spreading defects Various factors that affect the spreading process are
1.Ply alignment 2.Ply Tension or Slackness 3.Bowing 4.Splicing
Ply Alignment & Ply Tension The greater the variation in width or length alignment, the greater the waste in the precision cutting because the ends and sides must be trimmed to the narrowest and shortest plies. A tight spread will contract after cutting, resulting in smaller and skimpier components than what should be. A slack spread possesses excess length within the stipulated end of the spread. Cut components from a slack spread will tend to be oversized
Bowing Bowing is the distortion of filling yarn from a straight line across the width of the fabric. This would cause unbalanced stresses in fabric, resulting in slackness and tightness in the ply that will lead to undersized components. Also the garment component containing such a defect will tend to twist or distort in laundering or dry-cleaning.
Splicing & Static Splicing is the overlapping of two ends of fabric in a ply. A short or insufficient overlap will result in incompletely cut pattern sections and a long overlap will result in waste. Static in the fabric may cause a distorted spread, resulting in incompletely cut pattern sections. Static can be eliminated by either increasing the humidity in the cutting room or using static eliminators.
Some more possible spreading defects Not enough plies to cover the quantity of garments required. Narrow fabric Plies not all facing in the correct direction. That is, not all the plies are spread face down, face up, or face to face, as required. Mismatching of checks. Plies not spread accurately one above another ready for cutting.
Pattern Defects Marker making Defects Pattern Parts Missing Correct number of parts for all sizes not included by the marker maker. Mixed parts- Parts not correctly labeled in the marker; therefore, a marriage of wrong-sized parts. Patterns not facing in the correct direction on napped fabrics Patterns not all facing in the same direction on a one way fabric Patterns not aligned with respect to the grain line of the fabric. As a result, a garment may not drape or fit properly
Pattern Defects Marker making Defects Contd.. Line definitions poor (e.g., chalk, too thick, indistinctly printed line, perforated lay not fully powdered), leading to inaccurate cutting. Skimpy marking Either the marker did not use the outside edge of the pattern or the pattern was moved or swung after partial marking to squeeze the pattern into a smaller space in the interest of fabric economy. Alternatively, the pattern is worn around the edges and should be replaced. Generous marking A combination of points 7 and 8 results in the components being sewn together with puckering or pleating
Pattern Defects Marker making Defects Contd.. Marker too wide Garment parts at the edge of the lay are cut with bits missing Not enough knife clearance allowance Mismatched checks and stripes Notches and drill marks omitted, indistinct, or misplaced.
Cutting Defects Cutting quality is a prerequisite for quality in a finished product. In addition, cut work quality affects the ease and cost with which construction is accomplished. The quality of work leaving the cutting room is determined by how true the cut fabric parts are to the pattern; how smooth or rough the cut surface is; material or fabric defects in cut fabric parts; shade differences between cut fabric pieces within a bundle. In addition various factors in cutting that can affect the subsequent quality should be checked, such as under- or overcut, size, placement and sequence alignment of notches and drill holes, ripped or pulled yarns etc.
The defects that may arise in the cutting Frayed Edges May impede cutting time by clogging the knife action and / or mar the fabric with the rips or pulled yarns. The amount of fraying depends on fabric construction and finish. Improper cutting tools or dull knives cause excessive fraying in a pattern as section is cut.
Cutting room defects Fuzzy, ragged or serrated edges This is the result of the poor cutting. Such edges will impede sewing and / or diminish sewing quality. Such a condition is caused by faulty knife edges such as burrs, chips, or dullness
Cutting room defects Ply to ply fusion More common and troublesome. Adjacent plies in a block are fused together, which makes if difficult for the sewing machine operator to pick up a single ply quickly. Fusion occurs due to heat created by excessively high speed of cutting or by friction of a dull knife. To prevent fusion, check knife speed, keep knives sharp, place wax paper between fabric plies, and lubricate cutting blade.
Cutting room defects Single edge fusion Consists of a single ply whose cut yarn ends are fused to form a hard brittle rim on the cut edge. Sometimes, this is desirable to prevent fraying; however hardness and brittleness are undesirable it they impede sewing manipulation or may result in seams uncomfortable to the consumer.
Cutting room defects Pattern Precision Misshape or distortion of the pattern perimeter as cut. Whether it is under-or overcut is due to poor manual control of cutting machine and poor lines on the marker. To assure precision in a pattern, check markers before cutting, use tensionless spreading, or allow time for fabric to relax. After a cut, check the top, bottom, and middle plies against the pattern.
Cutting room defects Notches Notch size refers to the depth of the notch. If the depth of the notch is too great, the notch may show after a garment is sewn. If the notches are too small, sewing operators may have difficulty locating them quickly, resulting in decreased efficiency. Misplacement of a notch may be due to an improper spread marker, poor control of cutting machine with cutters notching tool stroking diagonally instead of vertically, incorrect marker in that notches for mating parts do not coincide. Check notch placement against mating pieces. Quality control in stitching may be a problem if notches are not aligned.
Cutting room defects Drilling The drill hole may be too large or too small in diameter. In addition, a drill may become too hot due to high speed or wrong size, causing the plies to fuse together at the drill hole. The drill must stroke vertically to the table for uniform placement throughout the bundle. Sometimes fabric properties are such that the slight movement of yarns in a fabric would close a drill hole. In such cases, it is necessary to drill holes with a marking fluid. The drill used for such purpose is hollow and carries marking fluid (ink) that is deposited at the drill point on the fabric as the needle is withdrawn. Such marks should last long enough so that further processing can be finished without difficulty, but should be easily removable after processing or in case of an error.
Glossary of Cutting room defects(Pattern, Marker, Spreading and Cutting room defects) Pattern Grading Defects01
Grade not conforming to Specification Measurements
Finished product not measuring to specified dimensions and component parts not fitting in relationship to notches, openings, and seams such as armholes, sleeve heads, neck bands, neck openings, side seams, inseams and waist measurements etc.,
Unbalanced patterns which would cause twisted seams, puckering, pleat