Which automatic sewing machine is best for safety harness?

"Reinforcement stitch" (by bar tacking or pattern tacking) sewing technology is necessary to obtain extra safety and durability in the manufacturing of height safety harness and fall protection equipment for people and property, made of Nylon, Polyester, Polypropylene, Webbing, Kevlar, Glass fiber, Vinyl, Leather and Canvas. If you are to bring production back in-house, for saving cost and improve quality, you need to have a specialized industrial sewing machine.

In today's ever widening world of heavy duty computerized sewing machines, how can a potential customer protect their interests and make a wise investment in a computerized sewing solution? How can any potential customer of automatic sewing machines know that they will be getting a machine suited for the job task they are trying to accomplish?

Now let us help you select a right "Ready-to-Operate" Sewing Automation Equipment for your project:

1, TOTAL THICKNESS OF HARNESS WEBBING

Sewing thickness is the first point you need to consider when select an industrial sewing machine. It determined by height of presser foot lift, hook type, needle bar stroke, needle penetration force and thread tension, etc. Here list the popular programmable pattern sewing machines for the manufacturing of height safety harness and fall arrest equipment:

MLK500-2516ECO: max sewing thickness 7mm, ideal for 2 ply harness webbing with each of 3.5 mm
MLK600-3020: max sewing thickness 9mm, ideal for 3 ply harness webbing with each of 3 mm
72600PLK: max sewing thickness 12mm, ideal for 2-4 ply harness webbing with each of 3mm
7273PLK: max sewing thickness 15mm, ideal for 2-4 ply hanrness webbing with each of 3.5mm
71008S: max sewing thickness 17.5mm, ideal for 2-5 ply harness webbing with each of 3.5mm
733PLC: max sewing thickness 28mm, ideal for 6-8 ply harness webbing with each of 3.5mm

2, SEWING AREA (THE LENGTH & WIDTH OF SEWING PATTERN)

The maximum working area of pattern sewing machine determines the maximum sewing area you can obtain. You should double check the maximum reinforced stitching area you need, both length (X) and width (Y) must be within range of machine's working area.

Some people intend to purchase one large area programmable pattern sewing machine for stitching both small size and large size straps and belts, it is really NOT a good idea. Small area programmable pattern sewing machine is better for small area reinforcement stitch (like seat belts and harnesses). If you are to sew small item with large area programmable pattern sewing machine, you might compromise on production efficiency and seam quality.

Below list the max. working area of each heavy duty automatic harness sewing machines:

MLK500-2516ECO: 250mmX160mm
MLK600-3020: 300mmX200mm
71008S: 130mmX60mm (Climbing rope sewing fixture is available as option)
7273PLK: 200mmX100mm
72600PLK: 250mmX160mm
733PLC: 250mmX160mm

3, SEWING THREAD SIZE

Thread size is the primary consideration for meeting the requirements of safety and durability seams for safety harness and lanyard. And sewing thread is very very important factor of the sewing quality. Light weight industrial sewing machines usually have small bobbin, needle and normal thread taking mechanism that cannot sew with thick thread. Heavy duty industrial sewing machines usually have big shuttle hook, needle and strong thread taking mechanis that can sew with very thick thread. Here list the Max. thread size of each programmable pattern sewing machine:

MLK500-2516ECO max. sewing thread: Metric#10,T-270, V277, 840Dx3
MLK600-3020 max. sewing thread: Metric#10,T-270, V277, 840Dx3
72600PLK max. sewing thread: Metric #8,V346, T-350,1100Dx3
71008S max. sewing thread: Metric #7, V415, T-400, 1300Dx3
7273PLK max. sewing thread: Metric #7, V415, T-400, 1300Dx3
733PLC max. sewing thread: Metric size #4, V693, 2000Dx3

4, MATERIAL DENSITY & STITCH DENSITY

In view of same material and thickness, the linear density and stitch density have great effect on stiffness of the slings and straps.
(1) If you use Mil-W-4088 military spec Nylon webbing or other extremely tough harness webbing, the needle penetration force of sewing machine must be taken into consideration, you need to purchase heavier pattern sewing machine or custom made programmable sewing machine with extremely powerful needle force.

(2) Seam strength is determined by (a) thread strength (thread type and size); (b)stitch count /number of stitches per inch; (c) weakening material from piercing with needle /type & weight of the Fabric);  (d)pattern of sewing; (e) stitch balance /thread tensioning. If the stitch density (stitch length and line distance) sets very high (see the green webbing in below picture), the synthetic fiber slings will become extremely hard and stiff, the thread will tend to break during sewing operation and the machine may be overload. In this case, you need a much stronger sewing machine.

5, SPEED OF SEWING MACHINE

Sewing speed biggest concern for customers buying their sewing equipment. Basically heavier industrial sewing machines run at slower speed, ligher weigth sewing machine can run at higher speed. So it is better to choose a highest speed automatic sewing machine that can sew the thickness of your harness webbing.

Below list the max. sewing speed of each heavy duty safety harness sewing machines:

MLK500-2516ECO max. sewing speed: 1600RPM
MLK600-3020 max. sewing speed: 1600RPM
71008S max. sewing speed: 600RPM
7273PLK max. sewing speed: 800RPM
72600PLK max. sewing speed: 1200RPMmm
733PLC max. sewing speed: 500 RPMmm

6, STRUCTURE & COMPOSITION OF FALL PROTECTION SAFETY HARNESS

Fall protection safety harnesses include innovative harnesses, lanyards, belts, horizontal lifelines, access systems, bulletproof vest carrier, body armor, parachute backpack, rescue and evacuation equipment, confined space solutions, all PPE or personal protective equipment needed for fall arrest protection and much more. In many cases, the structure & composition of harnesses is very complicated, so you need a custom made specialized sewing equipment, for example:

(1) If you are to sew the middle of full-body safety harness, life vest, bulletproof vest carrier, body armor, harness and parachute harness and backpack etc., you need pattern sewing machine with large clearance behind the needle, for passing the rest materials (as below picture).


(2) The working principle of programmable pattern sewing machine is the machine clamp material and move it during the sewing, so must leave a minimum border for clamping fixture (minimum 3-5mm margirn between stitching line and webbing edge of webbing). Sometimes, the sewing line is very close to the webbing edge or metal hook, we must develop some special clamps (as below picture).


Basically each safety harness and fall protection equipment contains a lot of bar tack seams: different sewing patterns, different sewing size, different construction (with or without metal hook), so all Ready to Operate Automatic Safety Harness Sewing Machine must have different clamps/fixtures.

7, PARTS AND WARRANTIES

Now review the parts availability and the warranties for the machines you’re considering. If your production line is running and something breaks within the warranty period, does the supplier have the part on hand? How long will it be under warranty? How long will it take to receive replacement parts when you order them?
When choosing a machine, spare parts availability is something that is often overlooked. If parts take weeks or months to get, your operation may be down during that period, so it is important to verify that parts are available and in a timely manner.

Note: above recommendation base on optimal stitch formation. A medium weight computerized sewing machine may be able to sew thick and dense harness webbing, but when running faster, it may see more wear and parts breakage. And you cannot obtain perfect sewing quality. See below photos of seam quality (bottom side of the webbing), the right thread tensioning is perfect, but the left stitch balance is poor, you can see the knots, because the thread take up lever is not strong enough, cannot pull bobbin thread to the middle of webbing. It not only influence the appearance of the finished product, also badly reduces the breaking strength of safety harness.

In the past years, we have developed full range of specialized and high efficiency programmable electronic controlled pattern sewing machines (with small area, large area and extra-large sewing are) to meet security required in this field. These heavy duty CNC sewing machines are particularly capable of assembling extra heavy weight materials using very thick thread. Particular for the production of synthetic slings, straps, belts, ropes, harnesses and webbing for serving high-end industrial markets such as cargo lifting and lashing, safety & protection, fire and rescue, marine, automotive, aviation, military, custom-made lifting slings for offshore, marine and industrial applications.

Why does HighTex require samples from the customer when setting up an automatic safety harness sewing machine?

We normally ask our customers to send sewn samples of the material that they want to use in the machine, as well as plenty of raw unsewn materials for testing, and also the thread that they would like to use for the sewn samples we run in the machine for the following reasons:

1. Certain factors will effect the sewing quality, for example stiffness materials, thickness webbing, nylon webbing woven density, thread size, thread type, sewing patterns, harness hardware / hooks and construction of rope lanyards. With sample material from the customer, we can custom make a sewing frame / clamp which will aggressively hold down the sample, and set the right thread tensions and sewing speed, as well as other calibration adjustments which will enable the machine to perform well in a production level environment.

2. We then test sew the machine over and over again to insure the machine will work flawlessly in production situations. This insures that you get a properly tested, adjusted, and ready to run solution out of the crate.

3. We will pre-program the machines according to the customers sewn sample and make a prototype of the customers production sample, so the customer can start production immediately when the machine is received.

What is the difference between HighTex automatic safety harness sewing machines and other Chinese heavy duty automatic sewing machines?

Enter Hightex --- a corporation founded on the principle of providing customized sewing automation for all phases of the heavy weight sewn products industry.

Other companies that manufacture sewing machines do exactly that -- they assemble components and test for correct operation, then ship the machine to the end user, unprogrammed, untested, without the proper jigging and fixturing necessary to complete the sewing projects of their customers.

So the customers must then hire an engineer to program their patterns into the machine, hire fabrication shops to build the required fixtures to hold the material, test the machine on a pre-production level, and then train employees and personnel to operate the machine. Such projects of a monumental undertaking require thousands of dollars, and in some cases tens of thousands of dollars to accomplish.

The first advantage of Hightex automatic industrial sewing machines is the customization.

We realize that customized sewing solution is the most suitable product for the highest possible productivity and quality. Our sale engineers will make clear your detailed sewing requirement, select the right machine for your application. Then our field engineers will build all the necessary clamping, jigging and fixturing to accomplish the sewing task, configuring these sewing equipment properly for customer sewing requirements.

The second advantage of Hightex sewing automation equipment is "Ready-to-Operate" (customers can use the machines immediately when they receive).

All HighTex heavy duty automatic pattern sewing machines and bar tacking machines will be thoroughly tested and gone over by Mingyuan Industrial Sewing Application Center.

This includes testing and checking all pneumatic, electrical, and computer systems for proper operation, programming the machine with all patterns supplied by the customers, and then testing the machine on samples that match exact customer specifications.

These operations save the end user many thousands of dollars in extra expense, eliminating the need for outsourcing the work required to get the machine in operating condition.

The third advantage of Hightex is the Spare Parts Package.

At Hightex, we realize how critical it is to keep your automation running. Let's face it, equipment breaks and machines malfunction. The key objective in a manufacturing environment is to minimize unplanned downtime. This package provides the necessary parts for the first 3-4 years of operation.

You can purchase the spare parts package together with machine, then no need to order any parts during this period.

If you have any questions or concerns, please feel free to contact us at info@automatic-sewing.com, thank you!