Pfaff Lockstitch Sewing Machine -Double Needle

by Engr. Kh. Mashiur Rahman | Jul 7, 2014 | Sewing & Production

Pfaff Lockstitch Sewing Machine

Lockstitch Sewing Machine -Double Needle of Pfaff and Bernina developed for garments industries. Double needle lock stitch sewing machine which produces stitches by interlacing of two threads is called double needle lock stitch machine. In this machine, there are two needles with the needle take up lever. It also contains two bobbins. For having two needles, there are two line of lock stitch in parallel. This machine produces durable stitches and is very popular in garment industries.

Function of Double Needle Sewing:

The double needle lockstitch is the tightest and most secure stitch which makes it a good choice for stitching the inseam of trousers. It also sews box pockets on safari jackets, light jeans and pyjamas and Suitable for sewing Shirts, Uniforms, Jeans and Women Underwear.

Sewing Machine Parts:

The sewing machine parts of double needle lock stitch is listed here.

• Bobbin winder
• Presser foot
• Stitch length dial
• Thread take cover
• Belt cover
• Lifting lever
• Needle bar
• Paddle
• Reverse lever
• Machine pulley
• Cone stand
• Finger guard

Specification of Double Needle Lockstitch Sewing Machine:

The specifications of a double needle lockstitch sewing machine is given below –

Features of the Machine with Needle Bar:

The features of the machine including needle bar is stated here-

• Stitches are produced by interlocking.
• It has two needles and two bobbins.
• Lockstitch sewing machine is very fast
• Bobbin,  needle bar and bobbin case are present in this machine
• Threads and  needle bar are supplied from cone.
• Double needle sewing facility

Safety for Double Needle Lockstitch Machine:

Please keep your hair, fingers and clothes away from the hand wheel, and motor while the machine is in operation, as well as never put anything near these parts, to prevent the risk of injuries by tangled into them.

Please never put your fingers under the needles or in the thread take up cover to prevent physical injuries when you turn on the power switch or operate the machine.

While the machine is in operation, the hook rotates at a high speed. Please keep your hands away from the area of needles to prevent any potential injury to your hands.  In addition please make sure to turn off the power of the machine while changing needles.

Broken needle may injure finger, eye or any where of the body and to solve it Use PPE (Needle guard, eye guard etc.).

Another problem is Machine belt pulley may cause any accident. And the solution is -Use pulley cover, machine belt cover & motor pulley cover during work time.

Pfaff Lockstitch Sewing Machine vs Operator / Supervisor:

The floors may some lines each which makes the total count of the lines to 15 in the whole unit. Since, in Bangladesh the labor cost is very low, therefore there are a lot of helpers in the lines and the automation is limited because of the same reason. That’s why one Pfaff lockstitch sewing machine is operated by one operator

The labor cost is around Tk.2400 ($34.3 or Rs.1800) per month, for a skilled operator as compared to Rs.2700 ($60 or Tk.3600) per month in India. Therefore, the automation is substituted by the use of intensive labor and the number of helpers per line is tremendously very much than most of the lines in India.

There are supervisors for each line who look after the production of the line and the proper working by the operators, in a way, supervisor is a face between the middle level management and the operators. The supervisors also take care of any problems faced by the operators and bring it to the notice of the middle level management, if needed.

Every floor has a floor manager who is assisted in his work by a junior manager and it is their responsibility to look after the production on the entire floor. The supervisors submit their hourly reports to them. The line balancing on the change of any style is also the responsibility of the floor managers.

There is a single production manager for all the 3 floors, and the floor managers report to him. It is the production managers who sees that which style has to be worked on which floor and which line and when.

Double Needle Sewing Mc – Daily Maintenance:  

Done by : Operators

Supervised by: Maintenance Personnel

Needle: Check whether the needle is bent or blunt or not. If it is bent or blunt change the needle and install it under the supervision of maintenance personnel.

Rotary hook: Clean the tail of thread, dust and lint in the rotary hook and bobbin case.

Lubrication: Lubricate the machine parts where necessary.

Time required: 10 minutes.

Cleaning the bobbin case and other possible parts:

Clean the lint, loose thread and other dirt from the shuttle of bobbin and bobbin case. Besides the table and other parts which cannot effect the setting must be cleaned.

Required time: 10 minute.

Double Needle Sewing Mc – Weekly Maintenance:

Done by : Maintenance Personnel

Supervised by: Maintenance Manager

Needle – Hook point timing: Check whether the needle – hook point timing is correct or not. If there lies miss-timing then adjust it.

The check points are

1. Needle – hook point clearance
2. The height of needle from its lowest position of upward stroke when the hook point reach at the center line of needle

• At the same time the distance between the hook point and the top end of the needle eye.

Required time: 10 minute.

The clearance between bobbin case holder and bobbin case holder bracket:

Check the clearance between the bobbin case and bobbin case holder bracket (1-1.5mm). Make sure that the hook will not touch bobbin case holder bracket.

Required time: 5 minute.

Adjustment of the needle and feed timing:

Check whether the adjustment of the needle and feed-timing is correct or not. If not adjust it through adjusting the timing belt.

Required time: 5 minute.

Presser foot pressure: Check whether the pressure of presser foot is proper or not. If not adjust it by adjusting the distance between the bottom washer and top of pressure bar guide bracket. And the bottom of work clamp must be kept parallel to the top of the work.

Required time: 5 minute.

Thread take-up amount:Check the amount of the thread take-up stroke, clearance between needle thread and thread take-up lever guide (.5-1 mm). Make sure that it is not more than necessary.

Required time: 5 minute.

Needle & bobbin thread tension adjustment: Check whether the standard operating range of thread take-up spring is accurate or not (6-8 mm). The tension at appropriate operating range must be checked.

Required time: 5 minute.

Needle Bar installation: It must be remembered during needle installation that the long groove of the needle is on the left and tightened with the needle clamping screw. Adjust the needle clearance and lift amount.

Required time: 2 or 3 minute

Stitch Length: Check whether the stitch length is appropriate or not. If not , push the reverse feed  lever halfway down, turn the dial until desired number align the pin at top and release the reverse feed lever.

It is remembered that the number, the longer the stitch length will be and the reverse sewing device is the automatic-resetting type.

Required time: 2 or 3 minute.

Needle Bar height: It is remembered that when the needle bar is in its lowest position the reference line on the must be at the lower end of the containing the needle bar. If it is not so, remove the needle plate, loosen the needle bar connecting stud clamping screw and adjust by raising or lowering the needle bar.

Required time: 5 minute.

Adjustment of Pressure on the material (fabric): The pressure on the material during sewing must be as weak as possible, but strong enough so that the material does not slip. Adjust the pressure through loosing the adjustment nut.

Required time: 5 minute.

Feed Dog Height: The standard height of the feed dog for sewing thin material is 0.8 mm, and for medium material is 1.00 mm and for thick material is 1.2 mm (when the stitch length is set to the maximum).

Adjust the feed dog height by loosening the screw when the feed dog is above the needle plate surface and move the feed lifting arm up and down.

Required time: 5 minute.

Feed dog angle: In order to prevent puckering, material from slipping the feed dog is to be raised or lowered downward at standard angle.

When the feed dog angle has been adjusted, check to confirm that the height of feed dog has not changed.

Required time: 5 minute.

Presser foot height:The standard height of the presser foot is 6 mm when the presser foot is raised with presser foot lifter lever. To adjust the presser foot height, loosen the nut of the adjustment screw and then the presser foot adjustment screw so that no pressure will be applied to the presser foot, then loosen the set screw and adjust the presser foot height by raising or lowering the presser bar.

Required time: 5 minute.

Double Needle Sewing Mc – Monthly Maintenance

Oil replacement and other interrelated checks:

1. Check lubricant or oil whether that is to replace.
2. Check bush leakage, oil seal leakage or age, vibration of oil and the flow of oil pump more or less than setting.

• Check rubber cushion seats, four corners of machine tool groove on which oil pan stands.

Required time: 10 minute

Rotary hook

Check rotary hook wear whether it is need to replace.

Required time: 10 minute.

Presser foot canal

Check its canal wear. If necessary replace it.

Required time: 5 minute.

Conclusion:

Sewing is a dominant process in the garment making, and it is still the best way of achieving both strength and flexibility in the seam itself as well as flexibility of manufacturing method. Much of the application of technology to clothing manufacture is concerned with the achievement of satisfactorily sewn seams. The objectives of sewing are the construction of seams, which combine the required standards of appearance and performance with an appropriate level of economy in production. This Pfaff Lockstitch Sewing Machine is also known as plain stitch machine. Here different type sizes of needle can be used as requirement. It is very popular in the garment industries.