What You Need to Know About Gore-Tex FFM Process?

Gore-Tex products are known for their quality and durability, and the company places a high priority on ensuring that its products are manufactured according to strict standards. One of the key steps in this manufacturing process is the Gore-Tex FFM process, which ensures that the shoes are produced using the same construction technology as under mass production conditions. 

In order to pass the FFM process, manufacturers must first submit pre-production shoes to Gore. These shoes will be put through a series of tests that simulate the mass production process, in order to ensure that they can withstand the complex bulk production that may have problems at any time. If the shoe passes these tests, the manufacturer is then acceptable to produce Gore-Tex shoes in bulk production.

In this article, we will be discussing the Gore-Tex Fit-For-Manufacturer (FFM) process, why Gore requires FFM, when it is needed, and what the specific process entails. Finally, we’ll provide some tips on how we pass the FFM testing process.

1. What is Gore-Tex FFM?

2. Why Gore Requires FFM? 

4. How many steps of Gore-Tex FFM process?

3. When does FFM needed?

5. How to pass FFM (Testing)?

6. FFM process & tips from TopUnion

1. What is the Gore-Tex FFM?

FFM is short for Fit For Manufacturer. The Gore-Tex FFM process is a critical step before the production of Gore-Tex products, which is the simulation of the relevant Gore construction technology process under mass production conditions. 

2. Why does Gore Require FFM?

This process is essential to ensuring the manufacturers are able to produce Gore-Tex Shoes smoothly in bulk production, which is important in the system of Gore`s FQS( Footwear Quality Standard).

3. When is FFM Needed?

The Gore-Tex FFM process is typically needed when a new factory or certified manufacturer is changing its construction method, materials, technology, or shoe construction. This could be in response to changes in consumer demand, new technology, or to improve the quality of the product. 

In any case, it is crucial that the manufacturer consults with Gore before making any changes, as the FFM process can be time-consuming and expensive. Failure to pass the FFM testing process can result in delays in production, or even the need to scrap an entire production run.

4. How many steps of Gore-Tex FFM process?

The Gore-Tex FFM process is a series of practice steps designed to simulate the mass production process.

1. The process begins with the submission of 25 pairs of pre-production shoes, which must be representative of the actual production shoes. This means that the samples should be made with the same materials, construction methods, parameters, technology, and process that will be applied in the regular production line. 
2. Document all the data and parameters in the whole process, including specific details e.g. machine, temperature, timing, and workers.
3. Then these 25 pairs of shoes will be put through a series of tests, which include breathability testing, centrifuge testing, and dynamic waterproof testing.
4. If the shoe passes these tests, Gore will issue the manufacturer the passed FFM testing report, which means that the manufacturer is then able to proceed with the production of the Gore-Tex shoe.  

5. How to Pass Gore-Tex FFM (Testing)?

A shoe or boot is deemed fit for production only if it meets the high standards of GORE-TEX footwear testing. 

5.1 Centrifuge Testing

The FFM samples will be tested with 30 minutes centrifuge machine based on Gore-tex Footwear Quality Standards (FQS). If no water appears on the window or on a paper towel and both shoes do not leak within the 30-minute cycle the pair passes.

TEST SPECIFICATIONS

RPM: 250 (+/- 3 for round type; +/- 5 for Square type)

Test time: 30 min

5.2 Breathability Testing

Gore has developed a special test method to determine footwear breathability. The test shoes are put on artificial feet that ”sweat” and placed in a climate chamber. Using moisture vapor transfer, a climatic factor is determined that represents a minimum standard of quality depending on the use of the shoe. 

The different cluster requires different levels of breathability.

5.3 Wet Flex Testing

The Wet Flex Test is used to determine the waterproofness of GORE-TEX Footwear. Test shoes are placed on flexible artificial feet which are equipped with sensors that do the flex in a water bath. 

5.4 Testing Result Definition

Production satisfaction (level 1): 

FFM pass rate 98% of factory centrifuge test = mass production start is possible

Re-start if the pass rate of level 1 is below 98%: analyze, improve & document the root causes

Specification satisfaction (level 2):

Centrifuge Test: min. 2 pairs pass rate 100% Gore lab

Footwear Breathability Test (FBT): min. 2 pairs pass rate 100% Gore lab

Flex Test: min. 2 pairs pass rate 100% Gore lab

If level 2 does not pass: analyze, improve and define the next steps.

6. Gore-Tex FFM process & tips from TopUnion

We start up the FFM process after styles have been approved, and here is our record for review.

6.1 Material hydrophobic Treatment

In order to make sure the Membrane could withstand Gore`s rigorous waterproof standard, the other materials used in the upper should be hydrophobic and specified as non-wicking, as per GORE-TEX standard. The GORE-TEX non-wicking standard states that a material (leather, textile, reinforcement, thread, lace, and all other components) shall not wick more than 1 cm within the 2-hour test period. 

With the hydrophobic layer, the whole upper material will become water-resistant.

From our experience:

Anti-wicking standard ≥ 16 hours, applicable to 12 hours static waterproof, dynamic 5W times or more.

Anti-wicking standard ≥ 20 hours, applicable to 15 hours static waterproof, dynamic 6W times or more.

And here are some tips about non-wicking treatment

• The action leather is easy to become hard after anti-wicking treatment, so the action leather material is not suitable for the tongue and collar parts.
• The leather is easy to shrink after anti-wicking treatment, so we always ordered 1-2% extra quantity.
• The effect of non-wicking treatment of 3M reflective leather, mirrored PU, microfiber, and nubuck synthetic is poor, so we always asked to treat from the sourced material supplier. Take care that mirrored PU is easy to change color.

• Velvet and microfiber material is easy to discoloration after anti-wicking treatment.
• If the material needed to be dyed, we always do the non-wicking first then die the material to fix the color better.
• For embossed material, we need to put on anti-wicking first and then do the embossing process.

6.2 Material Wicking Checking

PROCEDURE

STEP 1

• Pour the dye mixture into the wicking bath. The depth of the water will depend on the style of wicking bath you are using.

STEP 2

• Cut the material into long strips of 75MM*25MM: horizontal, vertical and oblique.
• Place a mark 1 cm from the bottom of the sample with a permanent marker for the water level.
• For zippers only: The water level is always at the top of the zipper stopper. For threads and other “floating” components: Attach weight at end of the sample.

STEP 3

• Place the sample into the wicking bath clip.

STEP 4

• Ensure the 1 cm line on the sample is at the water level
• Testing time: 2 hours. BATH SHOULD NOT BE COVERED DURING TEST.

STEP 5

• When test time elapses remove samples from clips and analyze them immediately.

ANALYSIS

STEP 1

• Blot samples on paper (for flat samples blot both edges and both sides) to determine the highest watermark at or above the 1 cm line.

STEP 2

• Measure the highest watermark starting at the 1 cm mark on the paper towel and visually on the sample to the nearest 0.1 cm.
• Note the measurement for each location: Face/Grain, Center, and Back/Flesh.

STEP 3

• Record all data in the test book.

PASS √

• If the total wicking measurement of the sample is ≤ 1.0 cm then this component meets the Gore standard.

FAIL ×

• If the total wicking measurement of the sample is > 1.0 cm then this component does not meet the Gore standard.

For heel counter samples, please note that heel counter material passed the non-wicking Gore quality standard in a half-processed state, i.e. skived and possibly pre-molded.

We have found that counter molder machine settings and the process of preparation and production can affect the test results of the whole shoe in the wet flex test.

6.3 Material Cutting

To prevent damage to the GORE-TEX membrane, the cutting plate must always be plain and free of sharp edges. 

We fold the Gore-tex fabric membrane side to membrane side and use the digital auto-cutting machine to avoid the sharp-edged cutting dies damaging the Gore-tex membrane.

Requirements on the number of folds when cutting GORE-TEX fabrics:

• GORE-TEX Four layers fabric – 4 folds maximum
• GORE-TEX Three layers fabric – 10 folds maximum
• GORE-TEX Two layers fabric – 20 folds maximum

And cutting direction varies for the different Gore-tex products.

After cutting, fix the GORE-TEX lining parts in the proper manner (not too tight!), and lay them out in the specific containers free of sharp edges.

6.4 Stitching

In order to remind workers to operate carefully and in place, in each process, we display the process notes in the most conspicuous place on the workbench.

6.41 ZIGZAG Stitching

The most important process in the stitching process is the waterproof membrane zigzag stitching.

Stitching Standard

• Number of stitches/inch: 8/inch
• Stitch width: 6mm
• Needle/thread information:16#Needle; 1×2 cotton thread
• Stitching needle: for 60/3 thread should be 80 R with a round top

Avoid butt seam for GORE-TEX lining stitching. It is required to align the mark to the edges, not to overlap, not be too tight to produce the wrinkle of the hosiery, and to cut the thread clean to prevent leakage.

Stitching Process & Tips

1. Stitch the vamp first.

2. Finish with the heel part.

• Avoid knots and material overlaps through correct tension.
• Membrane damage may be caused by the lower transport and drop feeder of the zigzag machine. The pressure of the transport foot must be adjusted correctly to not damage the membrane.
• No backstitches in the bottom area. 
• Cut the thread ends!

6.42 SEAM SEALING

Machine Set-up

• Check the overall air pressure of the seam sealing machine. 
• Make the Gore-Seam Tape centered.
• Adjust the tape tension, and the nozzle must be centered and distant according to the scorching point of the tape. (The scorch point is the setting at which the optimally visible scorching (melted knit threads) can be definitely determined)

Seam-sealing Process

• Tape from the zigzag position smoothly without stopping.

6.43 SUTER TEST

• The test is used to evaluate the seam waterproofness of sealed GORE-TEX Lining parts.
• Test pressure: 1.0 bar
• Test time: 5 min

PROCEDURE

1. Fill the pressure tester with distilled water. Ensure that the tester is full of water. The pressure tester is ready for use when the water comes up the pipe; and/or water is visible on the bottom plate. This ensures that during the test there are no air bubbles in the Suter machine.

2. Place the sample on the bottom plate (without wrinkles).

Backer facing downwards for sealing reasons

3. Cover the sample with a soft paper towel for better identification and localization of leakages.

4. Close the pressure tester with the top sealer.

Pull down the air pressure level. Required air pressure: 1.0 bar

5. Start the timer. Required testing time: 5 minutes

6. Test a minimum of 1 pair per hour per seam sealing machine. Recommendation: always test after changing the seam tape.

ANALYSIS

Check for water leaks during the test by inspecting the paper towel.

PASS √： If no leakage occurs after 1 bar / 5 minutes the sample meets the Gore standard.

FAIL ×： If leakage occurs during the test time the sample does not meet the Gore standard.

6.43 Other tips on the stitching process

• Thread ends: Use scissors with a rounded top to cut the thread ends.
• Hooks and rivets: The backs of the hooks, eyelets, and rivets must be covered (protected) with 1.5 – 2 mm of soft material (EVA).
• Overlap hammering: To avoid membrane damage overlaps, the upper margin (lasted constructions) of the form nip line (liner injection constructions) must be hammered before stitching the upper and lining together.
• Toe activation & Heel Counter fix the shape

Toe Cap：

The toe cap should be placed a minimum of 2 mm from the upper bottom edge. It is skived in the width of 8 – 10 mm on the top edge. It is not skived on the edge of the upper bottom part.

Heel Counter:

The heel counter should be placed a minimum of 2 mm from the bottom edge of the upper part. It is skived in the width of 8 – 10 mm on the top edge.

6.5 Upper Checking

In our factory, we engineered Gore-Tex Waterproof shoes with Liner Injection technology(DIP), which requires more strict and accurate craftmanship on the upper.

To avoid membrane damage all upper components in the area of the mould closure, the upper must have exactly the thickness that the mould was designed for.

So when checking the upper quality, we`ll also measure the thickness of the upper to make sure to keep the same material thickness in the nip line as defined by the mould.

If the materials are too thick:

Too strong print from the AL mould frame on the upper material.

AL mould frame clamps the upper material and the membrane – the shoe will not be waterproof.

You may change the position of the last in relation to the AL mould frame 1 – 1.5 mm up.

We have to increase the injected PU due to the larger volume of the mould (if not, the PU sole will be too soft).

If the materials are too thin:

The polyurethane material will flow through the open space (AL frame / upper) on the upper.

You may change the position of the last in relation to the AL mould frame 1 – 1.5 mm down.

We have to decrease the injected PU due to the smaller volume of the mould (If not, the PU sole will be too hard).

6.6 Assembling

After the stitching process, store the finished uppers in a properly organized manner and sent them to the assembly workshop. (the transport boxes must be big enough and free of sharp objects to the Gore-tex membrane).

1. STEAMING THE UPPER

• Steam temperature: 100 °C
• Time: 27 seconds
• Pressure: 3bar (depending on the thickness of the upper components)

2. LASTING

• Open the last in the heel area. 
• Slip the upper part onto the last properly.

3. CHECKING POSITION

• In order to make sure that the heel and toe parts are in the correct central position check the upper position of the last and make corrections.

4. LACE UP OR HOLD THE UPPER TIGHT

• Tie the laces or close the velcro to ensure that the opening stays symmetrical and no wrinkle on the upper.

5. HEATING THE UPPER

• The lasted upper must go through the heat setter. The temperature and drying time is dependent on the upper components (type and thickness of the material, etc.).
• Recommendations: The temperature in the heater: 90 – 120 °C
• Drying time: 1.5 – 2 minutes）

Tips:

Fully steam the membrane to dry it out. Otherwise, a penetration problem between the polyurethane and the membrane will occur.

6. ROUGHING

• Finish the roughing process all around within a width of a minimum 5 mm and remove the dust.

7. INJECTION

7.1) INSERT THE SOLE

• Insert the TPU or rubber sole as well as other functional parts in the mold bottom piston. Make sure that there is no wax or silicone on the membrane side before the injection process starts.

7.2) INSERT THE LASTED UPPER

• Insert the lasted upper into the injection machine. 
• We use a Robotic arm to make sure that the setting is correct (no pressure – just holding the position).

7.3) INJECTION

• Inject the liquid Polyurethane.

7.4) DE-MOLDING

• After approx. 3.5 minutes de-mold the injected shoe.
• We use an automatic application machine to release the shoes from mould (silicon or wax-based) must be sprayed on the mould always under an exhauster system.

7.5) COOLING 

• Cooling the shoes to shape the shoes better

7.6) DELASTING 

• De-lasting the upper and ready for testing.

6.7 Centrifuge Testing

We test the shoes in the centrifuge according to the centrifuge test instruction, 2 hours after injection.

About 2% of the daily production will be tested.

1) PREPARATION

STEP 1: Remove footbeds.

STEP 2: Lace footwear up snugly.

STEP 3: Fill the water level up to 2.5 – 3.0 cm under the lowest point of the GORE-TEX Lining or water tongue (whichever is lowest).

TIPS:

Fill the shoes on a table right next to the centrifuge machine. Avoid unnecessary moving of the filled shoes. Spilling must be avoided to not cause false failures during the test.

STEP 4: Insert the appropriate size shaft stabilizer into each shoe. The shaft stabilizer is only needed if the tongue or collar will fall in during the centrifuge cycle and in all tall boots.

STEP 5: Cover the bottom of each basket tray with a folded paper towel.

2) TESTING

STEP 1

• Make sure the exterior and sole of each shoe are completely dry. 
• Place one pair of footwear into the same level basket, positioned so that the heel faces in the direction the centrifuge moves. 
• Check the rotation label above the door. If the label does not exist yet, please tag one or mark the direction in another way. The toes must be placed flush with the edge of the tray.

STEP 2

• Shut the door and turn the machine on. Some machines have a safety feature built-in and may need to be reset in order to shut the door.
• The centrifuge should be set to 250RPM (+/- 3 for Round type; +/- 5 for Square type).

STEP 3

• Observe the test for the first 3 – 5 minutes of testing time for water traces on the window screen.
• If water traces appear, stop the test by pushing the red STOP button. Use the paper towels as a visual guide to determine if one or both of the shoes leaked.
• If only one shoe failed and is removed for analysis, fill another “dummy” shoe with water. (The weight of the dummy shoe, plus the weight of the water, should equal the shoe left to test.) Place in a basket in order to continue testing the non-leaking shoe.
• Periodically check for water traces on the glass throughout the testing cycle.
• The centrifuge will stop automatically after 30 minutes. The centrifuge has a safety feature where doors will automatically open once the machine has come to a complete stop.

STEP 4

• Lift the shoe up and visually inspect all paper towels for traces of water.
• Testing for each shoe is complete once a leak has been detected or when the shoe has endured a 30 minutes continuous cycle.
• Remove shoes from basket trays.

STEP 5

• Remove the stabilizer and empty the water.

STEP 6

• Place tested shoes on the shoe dryer.

3) ANALYSIS

PASS √

• If no water appears on the window or on a paper towel and both shoes do not leak within the 30-minute cycle the pair passes. 

FAIL ×

• If one or both shoes leak water within the 30-minute cycle the pair fails
• If water appears on the window or paper towel during the 30-minute cycle examine the footwear to verify if this is caused by a leak or water spilling out of the shoe. 
• Observe key areas to verify if water spilled out of the shoe. Spilling can occur from water sloshing out of a natural opening in the shoe, such as the water tongue opening. Spilling can occur when the centrifugal forces cause the shoe to distort, slump or tip. 
• If there is any question that the water observed on the towel or window is due to another reason besides a leak, dry the shoes for 24 hours and retest.

6.8 Breathability Test by Gore

After centrifuge testing, we picked up two pairs randomly to Gore`s Testing Lab for Breathability Testing and Wet Flex Testing.

Breathability Testing

Gore has developed a special testing method to determine footwear breathability. The test shoes are put on artificial feet that ”sweat” and placed in a climate chamber. Using moisture vapor transfer, a climatic factor is determined that represents a minimum standard of quality depending on the use of the shoe.

The breathability standard varies for different materials and construction.

6.9 Wet Flex Test by Gore

The Wet Flex Test is used to determine the waterproofness of GORE-TEX Footwear. Test shoes are placed on flexible artificial feet which are equipped with sensors, then submerged the shoes in five centimeters of water that take up to 300,000 steps (depending on Cluster) in a water bath. This is about the same as a 500 km hike across a wet meadow or through a stream. 

If a leak is detected, the simulator stops, indicating the location while tallying the number of flexes.

6.10 Dissection Analytics and Record

When the testing is failed, we will start the analytics process and record the reports.

6.11 FFM Passed Report

Once all tests have been passed, The Gore lab will issue the passed report to us.

Here is an example.

And Gore`s department will effect Perform Certification Audit, social compliance Audit, and Certification.

After that, Gore Footwear Application Engineer to initiate CMA (= Certified Manufacturer Agreement)

7. Conclusion

Gore-Tex shoes are made to high standards of quality. The process is time-consuming and expensive, but it’s necessary to ensure the waterproofing and breathability of their shoes. The centrifuge testing, breathability testing, and wet flex testing are all designed to simulate real-world conditions.

Gore provides technical expertise throughout all stages of the production process to help ensure our shoes are made to the highest possible standards. This has helped us become a Gore-tex-certified manufacturer and means that our shoes undergo even more rigorous testing to ensure they are 100% waterproof. We’re proud to have this certification, and it ensures that our customers can trust us to provide them with the best possible products.

In addition to Gore`s rigorous audit and test, we have also optimized our overall production process to ensure that our shoes are of the highest quality. We use state-of-the-art machinery and employ experienced craftspeople to create each pair of shoes. Our attention to detail ensures that each pair of shoes is perfect, and our customers can be confident they are getting a product that will last.

We are committed to providing the best possible products to our customers, and Gore’s technical expertise has been instrumental in helping us achieve this goal. We are grateful to Gore for their partnership, and we look forward to continued success in the future.

Please let us know if you have any questions or would like to discuss your specific needs. Thank you for your time!

FAQs

Q: What is Gore-Tex?

A: Gore-Tex is a brand of waterproof, breathable fabric that is used in a variety of outdoor gear and clothing. The fabric is made by layering a membrane of expanded polytetrafluoroethylene (ePTFE) between two layers of textile material. The ePTFE membrane contains millions of tiny pores that are too small for water droplets to pass through, but large enough for water vapor to escape, allowing for both waterproofing and breathability.

Q: Who owns the Gore-Tex brand?

A: The Gore-Tex brand is owned and trademarked by W. L. Gore and Associates, a privately held American company.

Q: How does Gore-Tex works?

A: Gore-Tex fabric uses a thin membrane of ePTFE that has millions of microscopic pores. These pores are too small for water droplets to penetrate, making the fabric waterproof. However, the pores are large enough for water vapor to escape, allowing the fabric to be breathable.

Q: Is Gore-Tex fabric durable?

A: Yes, Gore-Tex fabric is known for its durability. The ePTFE membrane is strong and can withstand a lot of wear and tear, and the textile layers on the outside provide additional strength and abrasion resistance.

Q: Can Gore-Tex fabric be washed and dried?

A: Yes, Gore-Tex fabric can be washed and dried, but it is important to follow the care instructions on the specific product or garment. It is usually recommended to wash it on a gentle cycle with mild detergent and to avoid using fabric softener. Tumble dry on a low heat setting or air dry.

Q: Is Gore-Tex material environmentally friendly?

A: Gore-Tex is committed to being environmentally friendly and sustainable. They have developed a range of products using recycled and environmentally friendly materials, and also have a recycling program that allows customers to send in their used Gore-Tex products to be recycled and repurposed.

Q: What types of products can be made with Gore-Tex?

A: Gore-Tex material is commonly used in outdoor gear and outdoor clothing such as jackets, pants, gloves, boots, and hats. It is also used in equipment such as tents, backpacks, and sleeping bags. Additionally, Gore-Tex can also be found in a variety of other products such as shoes, orthopedic products, and even medical devices.

Q: How many types of Gore-tex products?

A: Gore-Tex offers a variety of different types of fabric and constructions, each with its own set of features and benefits. Some of the main types of Gore-Tex products include:

Gore-Tex Pro: This is a heavy-duty fabric designed for use in extreme weather conditions and high-activity levels. Gore-tex Pro is highly durable and offers maximum waterproofness and breathability.

Gore-Tex Active: This is a lightweight and breathable fabric designed for fast-paced activities such as running and cycling. It offers a very high performance and level of waterproofness and breathability, while also being lightweight and packable.

Gore-Tex PacLite: This is a lightweight and packable fabric that is designed for use in a variety of outdoor activities. It offers a balance of waterproofness and breathability, making it a versatile option for a wide range of conditions.

Gore-Tex Infinium: This is a new type of Gore-Tex product that is designed to be used as a standalone layer or as an insulation layer. It offers a high level of breathability and moisture management, making it ideal for use in a wide range of outdoor activities.

Gore-Tex C-Knit: This is a new type of Gore-Tex product that is designed to be used as a back lining. It offers high breathability, moisture management, and enhanced comfort to the wearer.

Gore-Tex Shakedry: This is a unique type of Gore-Tex product that is designed to be extremely lightweight, highly breathable, and completely waterproof. The fabric allows any water that comes into contact with it to bead up and roll off, making it easy to shake and dry.

Q: How can I tell if a product is made with genuine Gore-Tex?

A: Look for the Gore-Tex logo or label on the product, which is a guarantee of quality and that the product has been tested and meets Gore-Tex’s high standards. You can also look for the Gore-Tex brand name on the care label or on the manufacturer’s website.