Expandable Braided Sleeves

November 28, 2025

40 years of expertise dedicated to protection!

Since 1985, GREMTEK has been supporting industrial customers with solutions for the protection, insulation and identification of cables, harnesses and components. Among these solutions, the expandable braided sleeve holds a special place: simple, effective, adaptable, and able to meet a very wide range of industrial requirements.

How does it work?

A braided sleeve is a textile tube made from monofilament and/or multifilament yarns in Polyester, Polyamide, Nomex®, PPS, fiberglass or tinned copper. It offers three essential advantages:

It expands: It widens to pass over connectors or complex geometries, then naturally contracts back around the cable.
It is flexible: It conforms to all shapes, even in tight or complex areas.
It is abrasion-resistant: It protects cables against vibrations, rubbing and repeated movements.

How is a braided sleeve made? Simple but technical!

Production is based on a controlled textile process.

STEP 1 – Yarns: monofilament or multifilament

Monofilaments

Multifilaments

Monofilaments : fsingle yarns Ø0.18 to Ø0.38 mm (Ø0.22 and Ø0.25 mm the most common).
Multifilaments : hundreds of micro-filaments; their size is expressed in decitex (mass/length).

These yarns exist in various materials (PET, PA6/6.6/11, Nomex^®, PPS, tinned copper…).

They are generally assembled in groups of three monofilaments of the same size and same material on the carriers of the braiding machine.
When necessary, we can combine several parameters such as yarn type (mono and/or multi), diameter, material, in order to obtain a braided sleeve with very specific properties. This makes it possible to achieve the best compromise between technical performance and the required function.

STEP 2 — Circular braiding

Braiders

Once the carriers are installed on the braiding machine, the monofilaments follow the paths defined by the machine. Some carriers rotate in one direction, others in the opposite direction, intertwining between each other. This synchronized movement creates a regular helical interlacing: this is the very structure of an expandable braided sleeve. The sleeve formed is then continuously wound onto large spools. Because the braiding process applies constant tension to the yarns, a continuous thermal stabilization step is then applied. It relieves internal stresses, homogenizes the braid, and ensures stable and reproducible expansion.

STEP 3 — Quality control

Each reference undergoes checks on:

Minimum/maximum expansion
Braid density
Abrasion resistance
Structural homogeneity
Dimensions
Visual aspect.

STEP 4 — Packaging

As needed: spools, coils, hot-cut custom lengths, kit assembly, etc.

Our technical expertise: R&D, laboratory and hot‑cut production

Airy braid

Dense braid

R&D know‑how

Our R&D department does not only select and qualifies materials: it also designs and specifies real textile architectures tailored to customer needs. We adjust several parameters to obtain the exact performance required:

Yarn type (mono, multi or a combination of the two)
Materials (PET, PA, Nomex^®, PPS, tinned copper…)
Monofilament diameter
Braid density and angle
Technical/economic compromise adapted to the project

Thanks to this textile engineering approach, we develop sleeves capable of meeting very specific constraints: extreme abrasion, high expansion, friction noise reduction, chemical or thermal resistance, EMI shielding, etc. You have a protection challenge: just share it with us!

Qualification & validation know‑how

Our internal laboratory makes us autonomous and responsive during qualification phases.
We carry out the main tests required by the automotive, railway and industrial sectors directly within GREMTEK:

Abrasion tests (PSA/RSA/OEM)
Thermal ageing (high/low temperature)
Fluid resistance (fuel, oil, coolant, additives)
UV and environmental tests
Dimensional and mechanical control
Fire pre‑qualification (UL94, EN 45545‑2 depending on material)

This internal capability reduces development times, ensures better repeatability, and allows us to adjust a textile construction quickly to match the specification perfectly.

Our unique expertise in hot cutting

Hot cutting is essential for delivering clean, functional sleeves that integrate properly into the customer’s application—yet it is one of the most difficult processes to master. We developed our own tools and processes to guarantee:

No fraying
A clean, fine and regular cut
A cut edge that remains flexible
Perfect maintenance of expansion
Stable quality over very large production runs

This mastery is not the result of chance: it required years of development, testing, and investment in appropriate industrial equipment. Today, we manufacture tens of millions of cuts per year, concrete proof of our expertise and the reliability of our process.

What are GREMFLEX^® expandable braided sleeves used for?

1. Automotive – robust and durable protection

The automotive environment imposes extremely demanding conditions: heat, vibrations, friction, repeated movements, aggressive fluids…
GREMFLEX^® sleeves are used for:

Engine harnesses
Tubes and hoses (fuel, coolant, AdBlue)
Air ducts
Cabin harnesses (seats, doors, headliner)
Cable paths exposed to friction

GREMFLEX^® PEA / GREMFLEX^® PEA-1, GREMFLEX® HAR-1, GREMFLEX^® PET 025-1 and GREMFLEX^® PA6.6 references are particularly suited for demanding environments (high abrasion, chemicals, mechanical constraints). They are among the products referenced by several major automotive manufacturers, with whom we work regularly through their R&D teams to validate or optimise our solutions according to their specifications.

2. Railway: fire/smoke compliance

The railway sector requires materials strictly controlled for:

Fire behaviour
Smoke emission
Toxicity

GREMFLEX^® PET-FR and GREMFLEX^® P-V0 are designed to meet EN 45545-2 requirements, as well as internal validations of major railway manufacturers.

Used in:

Passenger coache
Locomotives
Track and infrastructure systems
Railway electrical cabinets

3. Industry: flexibility and versatility

Industrial environments include a wide variety of applications:

Robots and mobile machines
Motor cables and guides
Electrical cabinets
Appliances and consumer products
Cable chain systems

GREMFLEX^® PET, GREMFLEX^® PET-L, GREMFLEX^® PET-SZ and GREMFLEX^® PET H&L meet needs for flexibility, abrasion, acoustics or chemical resistance depending on the sector.

4. Aerospace & Defence: high temperature and reliability

Some applications require very high resistance:

High temperatures
Low weight
Abrasion resistance

GREMFLEX^® NO (Nomex^®) and GREMFLEX^® PPS-L are preferred for severe environments.

Why use a braided sleeve?

✔ High mechanical protection
✔ Total flexibility
✔ Strong expansion capability (push-back effect)
✔ Lightweight and economical
✔ Chemical resistance
✔ Clean, simple and durable solution

GREMFLEX^® Quick Selection Table

GREMFLEX^® range: designed for all needs

The GREMFLEX^® range brings together all textile technologies developed by GREMTEK to meet every mechanical protection requirement:

Standard → very high abrasion
High expansion
Noise reduction
High temperature
EMI shielding
Chemical resistance
Fire/smoke requirements
Mono, multi or hybrid constructions

Our sleeves are qualified and validated by numerous automotive, railway and industrial manufacturers. They meet the main market standards:

S21 5101, D44 1959, 34-04-166, 39-06-008 (STELLANTIS / RSA)
ESDG9A-8C147 (FORD)
STJLR-51-5265 (JLR)
UL94 (fire behaviour)
EN 45545-2 (fire/smoke)
RoHS / REACH requirement

This recognition ensures direct compatibility with the constraints of major OEMs and confirms the reliability and performance of the GREMFLEX^® range in the most demanding environments.

Why choose GREMTEK?

Choosing GREMTEK means relying on a partner able to provide far more than just a product. Our value proposition is based on several pillars: • Proven industrial know-how With over 25 years of experience in expandable braided sleeves, we manage the entire process, from yarn selection to final packaging. • Production capacity for small to very large series We supply both specific kits and millions of pieces, with consistent quality. And we offer low MOQ for customer projects. • A tailor-made approach Each market—automotive, railway, industry, defence has its own constraints. Our R&D and laboratory will provide you with a rapid adaptation of textile construction, diameter or packaging. • Responsive technical support Material selection, technical recommendations, product choice, constraint analysis (abrasion/temperature/chemistry), prototypes, testing, validation. • Agile logistics with stock available in France Ensuring fast availability and continuity of supply. GREMFLEX^® braided sleeves are a reliable, flexible and economical solution for long-term protection of cables, harnesses and hoses. With a complete range from standard PET to high-temperature Nomex^®, including V-0, noise-reducing or high-expansion versions GREMTEK covers all current industrial needs.

A continuously evolving range

Our R&D team continuously designs and qualifies new references to meet the specific needs of our customers: innovative materials, custom features, or compliance with new standards.

Each project is an opportunity to adapt our products to your technical constraints and push performance even further

Our commitment

✅ 25+ years of experience in expandable braided sleeves

✅ Innovation, design, technical support, processing and responsive logistics

✅ Reactivity, proximity and stock availability

✅ Solutions adapted to the requirements of Automotive / Rail / Defence / Industry.

40 Years of GREMTEK: All About Expandable Braided Sleeves!

40 years of expertise dedicated to protection!

How does it work?

How is a braided sleeve made? Simple but technical!