Tips for Selection of Sewing Machines
by N. Rajashekhar

Operation
Before a decision is taken to buy a machine it is imperative to decide as to for which operation the machine is needed. It should be specifically decided whether machines are for shoe uppers, garments, leather goods or textiles. Choose Flat bed, Post bed or Cylinder bed depending upon the requirement.

Material, Thread & Needle
The number of needles should be specifically decided viz. single, double or multiple.

Stitch formation should be specified viz. lock stitch or chain stitch.

Specify what is the material that you are going to stitch, with needle and thread sizes. Sending a sample of work to the supplier is always best. Especially for binding -

1. Type of binding
2. Thickness of leather

If you do not specify correctly, it is possible that at times you may get a wrong machine, which may result in bad end product.

For instance : PFAFF has got different versions like A, B, B/C, C, C/D, D. The same kind of machines you may get in all of these versions which can be used for a light material to heavy material.

Some times the same machine model can be supplied for leather or fabric denoted by `L' or `S'.

In ADLER the same machine can be supplied with different versions like SL, L, M or S which can be used for very light material to heavy material.

Stitch Length
Always specify the maximum stitch length that you need in your machine (stitch/cm)

Hook Size
Hook size depends upon the work that has to be carried out on the machine. You can choose the hook size (small, medium or large), if the same kind of machine can be supplied with different sizes of hooks.

The difference between small and large hook will result in 60% extra bobbin thread capacity, by which we can save a lot of production time by eliminating changing bobbins frequently.

Feeding System
Some times for different operations you need to have different feeding systems or the same feeding systems with different kinds of parts that are involved in the feeding system. There are three different feeding systems for footwear sweing machine:

Normal Drop Feed (feeds the material when needle is out of the work) 
e.g. PFAFF 244, 563, 1243, 474

Compound Feed or Needle Feed (feeds the material when the needle is in the work) e.g. PFAFF 491, 471, 141

Unison Feed or Triple Feed ( two alternating pre-foot feeds the material when the needle is in work.) e.g. PFAFF 335 (binding machine)

For example:
A triple feed machine ensures superior climbing ability when sewing leather and crossing seams of different thickness.

Driven roller from top and bottom with needle feed ensures smooth work and better turning of material as the material is having point contact with the rollers.

In some operations by needle feed machines, with the needle in the work, it avoids ply shifting of materials.

Selecting suitable machines for type of work to be performed ( i.e. machine version with suitable feed and correct size, shape and type of presser footwear or presser roller, size and shape of feed dog) is very important for achieving good quality of seam.

Hook Placement (Left or Right to needle)
In some cases, when you are ordering single needle post bed sewing machines, it is better to mention whether you need a machine which is having a left hook or right hook. This depends upon the operation, which facilitates adoption of some special sub-classes (e.g. under trimmer)

Speed in Stitches per Minute
Decide how many stitches per minute you need for your machine. Higher the speed per minute, more is the productivity.

Working Guide
Selection of correct working guide for correct machine will ensure approximately 30 percent increase in productivity. Ask machine supplier for a fuides and gadgets catalogue.

Don't Leave the Option to the Supplier to Decide Specifications
At times, it is advisable to mention the roller size (small, medium and big). Small pressure roller is better for stitching smooth curves.

When you are ordering a Triple Feed machine, specify the lift (alternatively lifting of pressure footwear size)

When you are ordering a twin needle sewing machine - Specify the needle gauge (distance between the two needles)

Order the spare parts for two more extra needle gauges.

For good quality of two row corner stitching, it is advisable to have needle disengagable system.

When Ordering Trimming Devices:
Mention whether the knife mechanism should be from top or bottom. For example, when stitching top line of closed court shoe, it is advisable to order a post bed with trimmer driven from top.

Mention stitching margin to be left in your specification. it is advisable to take spares (needle plate) for 2 or 3 different type of stitching margins. This varies from ( 0.8 to 1.2)

THREAD TRIMMERS
Thread trimmers increase productivity and are very useful for big companies, provided maintenance is very good.

It the slack of thread is controlled well by technician, the thread used is finer.

At times it is better to take 4 machines without thread trimmer instead of taking 3 machines with thread trimmer.

When ordering Zig-Zag machines - Specify the maximum stitch width that you want to have on the machine.

Whenever ordering special kind of machine like Zig-Zag, Binding, etc., it is better to ask the supplier for different options of operations that can be done with the same machine just by changing some spare parts.

For example in Zig-Zag machine by changing few spare parts we can have cording seam also.

Lubrication system of the machine (automatic/manual)

SPARES
Ask supplier to specify spares for each machine with cost before finalizing the order. Usually we say 10 per cent spares without price details. Benefits of a price negotiation may be lost if prices of spares are increased or unwanted spares are sent.

GUARANTEE
Insist on a one year unconditional guarantee on machines.

The basis for selecting a supplier should be:

• Technology (i.e. current and not obsolete)
• Reputation/quality
• Past record in your company
• Performance of machine in other factories
• After sales service, e.g. service engineer at local office
• Availability of spares
• Delivery period

VISIT FAIRS
It is useful to visit fairs to keep track of latest developments of machines during the fairs. This helps buying the right machine for your factory.

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