Generic specifications of an overlock machine
- 1. Sewn Products, Machinery & Equipments-II Generic Specifications of an Overlock Machine By :- Ajay Gayakwar Presented to :- Mr. Ankur Makhija Bittu Singh Radhe Kumar Shubham Singh
- 2. Features Used to form over lock stitch. Sew both knitted and woven fabric. Makes an edge finish as well as to sew seams. In one operation, it cuts off the fabric to smooth edge and warps thread around the edge. Speed of machine – 8000 RPM The sewing speed must be between 6000-8500 SPM. Stitch Length – 0.8 to 4mm. Needles – DC x 1, DC x 27, DO x 5. A Needle with blunt or bent point should not be used in an edge cutter machine as it causes imperfection and may cause the needle to break . The size of the needle must conform to the size of the thread and should be suitable for the material being sewn.
- 3. Stitch Type and Number 2-thread overlock • 1-niddle and 1-looper thread. • Stitch type: 503 • Best for: Light weight fabric. • Application: serging edges, finishing seam edge and allowance. • Should be avoided in area that will receive stress. 3-thread overlock • 1-niddle and 2-looper thread. • Stitch type: 504 & 505. • Best for: Light weight & medium weight fabric. • Application: used for sewing woven and knits fabrics but should be avoided in area of stress. • Mostly used in skirts, lingerie, swimwear, etc.
- 4. 4-Thread Overlock • 2- needle and 2- looper. • Stitch type: 512,514 & 515(401+503) • Best for: Medium and heavy weight. • Applications: Suitable for sewing woven and knitted fabrics even in areas of stress. • Poor stretch hence not used in knitted garments. • Skirts, paints, sleepwear, blouses, etc. 5- Thread Overlock • 2- needle and 3- looper. • Stitch Type: 516(401+504). • Best for: Heavy weight materials. • Applications: Seaming woven and knits. • Safety Stitch. • Side seam of trouser.
- 5. Needles Needle used: DCX1, DCX27, DOX5 SHANK DIAMETER OF A NEEDLE MUST BE MINIMUM 2.02mm. BUTT TO EYELET : the length is fixed even when thickness of needle varies. LENGTH OF NEEDLE: DC*27 ,The total length is fixed since it is required to scoop looper thread at the needle tip. They feature a sharp point that is suitable for all fabrics.
- 6. Threads NEEDLE TO THREAD RELATION if the needle is too big, it will drop to the bottom of the thread If the needle is too small, it will stick at the top of the thread If the needle is the right size, it will slowly spiral to the bottom of the thread Needle Bar Stroke NEEDLE BAR STROKE MUST BE 24.5mm. Greater distance between point of needle and throat plate easier will be the penetration.
- 7. Looper Loopers serve to create thread loops that pass from the needle thread to the edges of the fabric so that the edges of the fabric are contained within the seam. TYPE OF LOOPER: blind looper and eyed looper(only used in overlock) Stitch type 503 : 1 looper Stitch type 504 : 2 loopers Stitch type 505 : 2 loopers Stitch type 512 : 2 loopers Stitch type 514 : 2 loopers Stitch type 515 : 2 loopers Stitch type 516 : 3 loopers
- 8. Feed Dog Differential feed must be used. Differential ratio : 1:0.7~1.2 No. of feed dog rows : 2,3 Pitch Standard pitch : 1.5mm This type of pitch is suitable for medium- weighted materials .
- 9. TYPE OF PRESSER FOOT • THE PRESSER FOOT PRESSURE FOR SEWING BASED ON NORMAL CONDITIONS SHOULD BE SET TO 2.5. • PRESSURE FOOT SHOULD BE SELECTED SUCH A WAY THAT THEY MAKE THOUGH SEWING JOBS EASY. • THE OVERLOCK FOOT WILL NEATEN SEAM EDGES ON FABRIC ON YOUR SEWING MACHINE. IF YOU DON'T OWN A SERGER OR IT IS NOT SUITABLE FOR YOUR PROJECT, THIS FOOT IS A NICE ALTERNATIVE.
- 10. ALTERNATIVE PRESSER FOOTS Elastic Foot for Serging Gathering Foot for Serging Pearl Sequence Foot for Serging Piping Foot for Serging
- 11. PRESSER FOOT LIFT Maximum lift of presser foot : 8 mm Minimum lift of presser foot : 5.5 mm PRESSER FOOT PRESSURE Maximum presser foot pressure : 63.7N (6.5kgf) BY Foot lifter
- 12. DIFFERENTIAL FEED RATIO • SINGLE NEEDLE OVERLOCK FOR GATHERING 1:1.75 (MAX. 1:3.8), FOR STRETCHING 1:0.7 (MAX. 1:0.6) • DOUBLE NEEDLE OVERLOCK FOR GATHERING 1:2 (MAX. 1:3.8), FOR STRETCHING 1:0.8 (MAX. 1:0.6) • SAFETY STITCH OVERLOCK FOR GATHERING 1:1.75 (MAX. 1:3.8) FOR STRETCHING 1:0.7 (MAX. 1:0.6)
- 13. THROAT PLATE A sewing machine throat plate has holes and/or slots for the needle to pass through as it moves up and down. Allows the sewing machine feed dogs to emerge from below to grip the fabric and help move it forward. 1- Needle overlock throat plate Throat plate slot Location of the auxiliary feed dog teeth Feed dog groove Location of a cloth cutting knife Needle entry
- 14. TYPES OF THROAT PLATE 2- Needle safety stitch throat plate 2- Needle overlock throat plate 1- Needle overlock throat plate
- 15. KNIFE MECHANISM The knife must be sharp enough to cut the materials. Adjustment of the position to the materials trimming knife. There are two types of knife used in overlock machine. I. Upper knife II. Lower knife The upper and lower knives of modern models are attached at bottom part of serger. Older models of overlock sewing machines have another design. One knife blade is mounted on top, second blade is attached on bottom part of serger. Distance between needle and knife varies
- 17. SENSOR • WHEN THE SENSOR DETECTS A MATERIAL EDGE, IT MUST IMMEDIATELY STOP THE SEWING MACHINE AND ACTUATE THE THREAD TRIMMER. Automatic tape cutter and chain-off thread trimming Pneumatic side cutterPneumatic flat cutter
- 18. TYPE OF MOTOR • A Servo motor, however, does not run until you engage the pedal. Without the motor running, it makes no noise at all. • Consumes approximately sixty to eighty percent less energy then the clutch motor. • Control the speed of the motor with a switch that lets you adjust between 0 and 3300 RPM. FUNCTIONS VALUE OUTPUT(watt) 3/4 H.P (450-550w) FREQUENCY(50-60 HZ) SPEED(rpm) 3500-5000 RPM VOLTAGE Single phase: 220V Servo Motor
- 19. Lubrication Dry-head technology leads to excellent seam quality and higher productivity. It substantially removes oil splashes to eliminate oil stains on sewing products. The frequency of stain removal or re-sewing is removed. Advanced dry technology such as special surface treatment is applied to the major drive unit . The machine does not splash oil after a long period of use. General Requirements Power Requirement - Single phase 100~120 V, 200-240 V, 3-phase 200-240 V Power Consumption - Rating 425 VA Motor Output – 750 W
- 20. Machine Bed Over-edge stitching is generally done on side-bed. It has a small working area. It is specialized for overlock machines. Attachments Backlatching capability of an overlock machine eliminates the need for bartacking. The chain-off thread is tucked into the seam at the beginning of sewing to secure chain-off thread and prevent the finished seam from coming undone. It leads to excellent seam quality and increased productivity.
- 21. Attachments Chain-off thread trimming device – One touch type chain-off thread trimming device, pneumatic or electromagnetic is preferred. Presser foot lift – It is lifted pneumatically. It can also be lifted with heel treadle. Ease of operation decreases operators’ fatigue. Electric hemming device – It prevents fabric mis-alignment which tends to occur in the cross seam sections of blindstitch hemming operations. The sensor detects the cross seam sections to automatically slide the hemming guide and keep the fabric from mis-aligning.
- 22. Comparison of different brands Specifications Juki Consew Brother(Home-sewing) Pegasus Application Light, medium or heavy Light to mid-heavy Light to medium Light to heavy Maximum SPM 7000 8500 1300 9000 Feed system Differential feed Differential feed Differential feed Differential feed Maximum stitch length 4mm 3.8mm 4mm 3.8 Needle bar stroke 24.5mm 24mm - 24mm Needle DCX27 DCX27 DCX27 DCX27 Presser foot lift 7mm 5mm 4mm 7mm Lubrication Semi dry head Automatic Automatic Semi dry head Differential feed ratio 1:0.7~1:2 1:0.7~1:2 2:0.7 0.8~1.8 Power requirement 200~240V 200~240V 110V 200~240V Power consumption 425VA 425VA - 425VA Weight 6.3kg 7kg 6.1kg 6.5kg
- 23. Conclusion Specifications General Stitch type Overlock Stitch number 503, 504, 505, 512, 513, 514, 515, 516 Application Sewing, serging, seaming Maximum sewing speed 8500 Pitch of feed dog 1.5mm Feed system Differential feed Maximum stitch length 4mm Needle bar stroke 24.5mm Shank diameter of needle 2.02mm Type of throat plate Overlock throat plate Needle tip Sharp
- 24. Conclusion Specifications General Number of rows in throat plate 3 Needle DCX27 Maximum pressure by presser foot 63.7 N Lift of presser foot 8mm Lubrication Dry head Power requirement Single phase 220 V Power consumption Rating 425 VA Total weight 6.5 kg
- 25. References Juki.co.jp . Model List. Retrieved from : http://www.juki.co.jp/industrial_e/products_e/all.html Pegasus.co.jp . Retrieved from : https://www.pegasus.co.jp/en/machine/series/ Consew.com . Retrieved from : http://www.consew.com/List/Chainstitch-Sewing/Overlock-Coverstitch Brother-usa.com . Retrieved from : http://www.brother- usa.com/homesewing/productlist.aspx?cat=sergers Singerco.com . Retrieved from : http://www.singerco.com/products/category/sergers Pfaff-industrial.com . Retrieved from : http://www.pfaff-industrial.com/de/portfolio/pfaff-maschinen