Guides for furniture glides

Performance

We expect a lot from furniture glides. They need to do their job effectively while at the same time forming an integral part of the overall design concept. Often we need them to function faultlessly and unobtrusively throughout the entire lifespan of the piece of furniture.

Furniture glides are frequently part of the design of new pieces of furniture, whose development involves extensive design and function studies by furniture designers and manufacturers. They can also be purchased as ready-made products for use in existing furniture designs. In the case of furniture that is rarely moved or subject to light use only, choosing the right furniture glide is somewhat less important. However, particularly when it comes to chairs, choosing the right glide is critical and requires careful attention.

Chair - flooring - use

Choosing the correct furniture glide will ensure that:
• The floor is not damaged
• The floor does not damage the glide excessively (soiling, sealing with hard materials, etc.)
• Moving the chair does not make too much noise
• The chair is relatively easy to move but does not slip when someone sits down on it
• Misuse ( e.g. leaning back on the chair, tipping the chair over) is tolerated without damaging the floor

Types of furniture glides

A number of different types of furniture glides have been developed in recent decades:

1. Single-part glides - commonly used plastics include polyethylene (PE), polypropylene (PP), po1yamide (PA), polyoxymethylene, (POM) and polycarbonate (PC)
2. Two-part or multipart bonded glides with glued, welded or injection-moulded slide inserts
3. Two-part or multipart bonded glides with mounted slide inserts

Single-part glides are generally inexpensive and are used where a flat, unobtrusive fittings is desired. The main factor determining the size of the glide is the manner in which it is affixed to the chair, unless the design aspects are more important. Types two and three are more expensive but provide a better match with the type of flooring, without compromising the strength and stability of the chair. With type three, the insert can be replaced if necessary, but the glides are generally somewhat bigger as a result.

Slide inserts (forms and materials)

The following forms and materials are found for slide inserts and moulded, mounted or affixed glide parts:
• Felt stamped parts (pressfitted, mounted or locked into place with an overmoulded plastic frame, glued on, or welded on using friction welding)
• Single-part hard plastic mouldings (PE, PP, PA, POM, PC, etc. - overmoulded, glued, welded on using friction welding, pressfitted, mounted, or locked into place)
• Stainless-steel feet (flanged around the glide)
• Chrome- or nickel-plated steel feet (flanged around the glide)
• Single-part soft plastic mouldings: elastomers and thermoplastic elastomers - overmoulded, glued, welded on using friction welding, pressfitted, mounted, or locked into place
• Bonded composite mouldings consisting of flexible brackets and easy-gliding foil: elastomers and thermoplastic elastomers (TPE) with foil made out of polytetrafluorethylene (PTFE, e.g. sold under the brand name ™Teflon, ultrahigh molecular PE, or crosslinked ultrahigh molecular PE)

What can chair glides do, and what can‘t they do?

Chair glides (and slide inserts for chair glides) are subject to normal wear and tear. They need to be periodically inspected and maintained, especially when used with sensitive floors. There is no one floor glide that is suitable for all types of flooring: although some materials can be used on any type of flooring, this always comes at the cost of durability (e.g. PTFE, felt) or functional incompatibility (e.g. TPE-U/PUR = excellent adhesive properties or PTFE = extremely low friction or adhesive resistance).

The durability of the chair glide depends critically on choosing the correct type of glide.

Here, the following factors are important:
• Surface area that the chair glide or slide insert will rest on in relation to the actual load (weight of person + weight of chair)
• Correct choice of material for the slide insert - this should suit the type of flooring
• Pattern and type of use
• Colour of slide insert

For various reasons (e.g. design, cost, weight), small-diameter round steel tubes or smalldiameter tapered steel tubes shaped using hydraulic pressure are often used in tubular steel chairs. Often, the expectations of the furniture manufacturers are that the base of the chair glide will not be too big in relation to the diameter of the steel tube. However, as the diameter of the tubular steel decreases, wear and tear on the slide insert increases geometrically, as does the amount of pressure exerted on the floor. Keeping the chair glide in place also becomes increasingly difficult with smaller tube diameters. In the case of cantilever chairs and tubular steel chairs which do not have vertical legs made of steel tubes with smaller diameters (18-22 mm), this is less critical if the slide base can be long enough.

The choice of material for the slide insert depends on the characteristics of the flooring and the desired level of comfort. The floor manufacturer should indicate suitable materials for furniture slidcs and the minimum slide surface area per chair for its products. lf a low level of noise is important, it should be borne in mind that with materials such as felt, elastomers and thermoplastic elastomers, the softer the material, the faster it wears out.

lf, on the other hand, easy movement of the chair is important, it should be remembered that PTFE and ultrahigh molecular PE or cross-linked ultra high molecular PE cannot be moulded using standard thermoplastic techniques - instead they are generally used as feedstock foils or sintered pre-forms for making bonded composite moulded parts. The durability of these products is limited: despite the low level of friction and hence abrasion, only average durability can be expected in the case of intensive use.

School chairs and stacking chairs for use in mass seating are particularly demanding, due to both the type of use and the users themselves. Good floor cleaning and regular inspection and maintenance is essential. Often, vandalism is also a factor - in such cases the chair glides will not taste forever, however strong they are. lf the floor is not sensitive, natural-coloured slide inserts should be used to ensure that any marks can be removed without trace: coloured slide inserts and glides can leave marks that are difficult or even impossible to remove.

The following criteria should also be taken into account:
• Care and cleaning of the floor
• Type of flooring
• Quality of the floor design

Floor care and cleaning, depending on the level of soiling and wear and tear, are essential. Small, hard particles of dirt become ingrained in all types of slide bases. When the chair is moved, they then scratch the floor at the same time as wearing down the slide base. In steel or stainless-steel feet, this leads to sharpedged grooves which in turn damage the floor. Some flooring manufacturers seal their floors with a top coat containing corundum to protect it from scratches. Corundum is a very hard abrasive material and can quickly wear down furniture glides and slides. The type of flooring determines the level of abrasion and grip, as well as the level of noise created when moving the chair. A less or more easily sliding chair glide should be chosen accordingly, and extra soundproofing glides added if necessary.

The floor on which the chair is placed should be smooth and free from bumps. Rough floor tiles with protruding edges and sudden thresholds or doorstops can put chair glides beyond repair in a very short time. Choosing the right type of flooring can also be critical for ensuring a low level of noise.

In many cases, the furniture glide will actually outlast the item of furniture. Often a simple straight glide from our GL product line, in a natural colour, or an angled glide from our RS line, also in a natural colour, will be a satisfactory solution. These products are also very easy to replace in the case of excessive wear and tear.

Private and public tenders for seating systems

Where a tender specifies the type of chair glide to be used, the floor design, floor type, chair glide and type of use must all match in order to ensure realistic durability for the specified level of floor care (cleaning, inspection, and maintenance of floor and chair glides). The tender documents will indicate how long the construction materials, objects and different components used should last. In many cases, the chair glide is the weakest link in the chain: if it is faulty, it can potentially damage the floor by causing excessive stress.

In terms of type of use, stacking chairs for schools, halls and large venues place the greatest demands on chair glides. Careful thought needs to be given to what chair glide is most suitable for the particular type of use in question.

lf tilt glides are chosen, it should be remembered that these can twist in the opposite direction from that required to support the chair leg. The people responsible for the chairs must make sure that the bases of the tilt glides are always flush on the floor, and that when the chairs are unstacked they are placed carefully on the floor rather than thrown onto it. lf they fail to do this, the tilt glides can come off or be damaged when the chairs are unstacked or in use. Natural coloured PE angled glides - our SRS and RS product lines - can be a safer, if somewhat less elegant, solution: they are sufficiently soft and do not mark the floor with their colour, but wear out more quickly.

We offer all common types of slide base
• Stainless steel
• Felt (various qualities, natural or dyed)
• PA (natural or dyed)
• PE (natural or dyed)
• POM (natural)
• PP (natural or dyed)
• PTFE (natural or dyed)
• PVC-P (soft; natural or dyed)
• Steel (nickel- or chrome-plated)
• TPE (-U, -V, -E; natural or dyed)

TPE-U offers the most effective stop/non-slip function on a wide range of different floor types, combined with very good durability.

PTFE offers the best glide effect (dynamic and static friction) on a wide range of different floor types.

Some mounted slide inserts are easy to replace. Often, however, replacing the whole glide can be cheaper and easier than replacing the slide insert. Natural-coloured slide bases are recommended, as they can be used in a wide range of settings. They also do not leave marks if the floor or glides contain vinyl (PVC, EVA, etc.).

During wet cleaning of floors, furniture with felt or steel (nickel- or chrome-plated) slide inserts should be removed until the floor is completely dry. The detergent used must be compatible with the material in the slide base and not react with it in any way.

We recommend the following combinations of floors and furniture glides. Floors must be cleaned and maintained regularly, and the chairs should be used with proper care.

The level of comfort varies for the different combinations, as does the durability of the slide inserts:

• Laminate floors (not sealed with hard materials: Depending on sensitivity and anti-slip factor, soft to medium-hard felt, TPE, PE, PP or PVC-P (natural)
• Parquet (not oiled or sealed with hard materials): Depending on sensitivity and anti-slip factor, soft to medium-hard felt, TPE or PVC-P (natural)
• E/astic flooring for sports halls and similar: Depending on sensitivity and anti-slip factor, stainless steel, medium-hard felt, PA or POM
• Linoleum: Depending on sensitivity and antislip factor, soft to medium-hart felt, TPE or PVC-P (natural)
• Soft, smooth natural stone: Depending on sensitivity and anti-slip factor, soft to medium-hard felt, PTFE, TPE or PVC-P (natural)
• Soft, raw natural stone: Depending on sensitivity and anti-slip factor, TPE or PVC-P
• Hard, smooth natural stone: Depending on sensitivity and anti-slip factor, mediumhard felt, PTFE, PA, PP, PE, POM or PVC-P (natural)
• Hard, raw natural stone: Depending on sensitivity and anti-slip factor, POM, PA, PP, PE or PVC-P
• Hard, smooth ceramic tiles: Depending on sensitivity and anti-slip factor, mediumhard felt, PA, POM, PVC-P or TPE
• Carpet/textile floors: Depending on sensitivity and type, stainless steel, PT, FE or PVC-U (hard PVC)
• Vinyl floors: Depending on sensitivity and anti-slip factor, felt, TPE, stainless steel, PA, PP, PE or POM
• Composite concrete, exposed concrete: POM (natural), PA (natural) or stainless steel

Material information without any obligation Felt

Industrial Processed Felt

Is demanded beginning with the middle of eighties of 20th century for facing of plastic furniture glides due to preserve sensitive floors/ground areas and due to silencer of moved seating furnitures. In opposit to some plastic glide facings scratching or abrasive piling on sensitive floors (parquet, polished/smooth lime stone floors, etc.) will be prevented and instead of it a higher abrasive loss of felt will be accepted. For this task strongly depending on floor cleaning (dry suction cleaning - avoiding contact with water and other fluids; felt moistens and will be strongly abraded) felt can only be a compromise between preserving/silencer and wearing. Industrial processed felt is practically available in all dimensions, forms, cuts and in various specifications, like coloured, self-adhesive, siliconized, flame-retardent, dry cleanable, limited water resistant, short time water-repellent, antistatic, etc. One essential feature is its specific range of density, which mostly enfolds 0,2 - 0,7 g/cm³. Qualities are processible hard as wood or soft as wadding. With increasing density raw material charge and requirements to converting plants increase.

Entanglement

Wool and other animal hairs felted by friction, warmness, humidity and lye, as upforming scales of fibre surfaces jam with each other unresolvable. Who unawares has washed a wool sock with a wahsing machine knows the effect: the sock is shrunk several sizes and got very solid. What is an mishap in the household will be processed by industrial felting by machine-made bulging, knocking and pressing. This kind of felting with jammed upforming scales is a specific feature of animal hairs/wool. In contrast other fibres will be mechanical felted/entangled by nails with barbed hooks (look at Manufacturing Technologies).

Felt-Definitions and Features

Felt is a layered, textile, non-woven, pressed fleece fabric made of wool and/or fibres, which is principle a fibre composit. It will be processed from single fibres, which lay tangled one upon another and partially interleaved entangled without spinning, weaving or meshing. Cleaned combed, maybe coloured and to fleece processed raw wool and/or fibres will be pressed/stabilized into a solid fabric (textil flat material or mats with defined features according to DIN 61205) by mechanical treatment (felting and milling), mostly with thermical and chemical support. Substantially felt is a two-dimensional pressed fabric in multi-layer array with low three-dimensional weave. On condition of shear stress felt tends to delaminate in layers.

Felt-Variants

Variants of felt will be differentiated between origin of raw material or manufacturing process. The term wool felt describes for example the origin of fibres (substantially sheep´s wool but other suitable animal hairs, too), in opposit to synthetic felt (synthetic fibres of Nylon, polyester, polypropylene, polyacrylamide, Normex, Kevlar, glass, etc.) or felt made of plant fibre (cotton wool, rayon staple fibre, kapok, ramie (bast fibre), jute fibre, etc.). Real felts are made of fibre blanket, pseudo felts are made of woven flats, which are felted in a shaping machine. Felt can consist of one raw material, but also of mixtures of different raw materials. The terms needle felt, pressed and squeezed felt, woven felt, press felt or cloth felt refer to the manufacturing process.

Manufacturing Technologies

Wet felting (according to DIN 61210 pooled unter the term of pressed and squeezed felts) of unbound fleece with warm water (steam) and soap (alkaline felting support) is the traditional, craftman´s processing of wool or animal hairs. In combination with warm water and soap the top level scale layer (cuticula) forms up, the scales of hairs. Simultaneous pressing and squeezing of fibres cause a penetration of each other. The formed up scales wedge so strong in each other that they are unresolvable. The workpiece shrinks strongly and forms a solid material (textile flat). The final form can be worked out in one piece. Pressing and squeezing felt is very expensive in time and substantially will be processed in little scale in handcraft, hobby or education. Pressed and squeezed felt has normed features according to DIN 61200 and DIN 61206 Part 2. The strength of pressed and squeezed felt is given by its densitiy. Due to animal fibres, partially in mixture with rayon staple fibres pressed and squeezed felt is a biodegradable natural product.

In the dry felting process wool is formed with specific needles. This method is the ancestor of needle-punching with a needle girder. In the process of needle felting fibre blanket will be repeatedly penetrated by needles with a barbed hook (360 up to 720 penetrations each square centimeter), arrayed vice versa like a harpoon, so that the fibres will be pushed into the felt and the needle goes out whithout resistance, with the effect, that fibre clusters will be drawn to the rear side of fibre blanket and interlock to a solid flat. Needle fleece materials are not only made of wool, but practical of all other fibres (for example sythetic fibres, look at Felt - Variants). Besides jamming will be processed with pulsed water jets or with binders. In this case fibres without scale structure are suitable (for example sythetic fibres, look at Felt - Variants). Mostly needle felts are stiffened with the support of chemicals.

Product Ranges

Wool felt and other non-woven materials are used in stamp pads, for machine damping, for noise insulation, for polishing glass, granite and some metals. Oil-moisted felt pads are used for lubrication of machines. Due to its long-term flexibility felt is suitable for damper in pianos and other musical instruments. Made of wool felt are also hats, shoes and other articles of clothing. Furthermore felt is used for screens, filter and sealing purposes.

Applications (furniture glides)

Felt is used for furniture glides for several years. Flat stamping felt parts are mounted in furniture glides by pressing, gluing, welding (friction or vibration welding) or injection moulding. The durability of these four methods with the same felt quality is about the same. The costs or product prices rise extremely when welding on or injection moulding. During welding on process the felt loses about 1,5 mm of its original thickness.

In case of gluing a ready pre-assembled and self-adhesive felt is the appropriate choice since the felt manufacturer provides for a consistently high adhessive quality during the production process. Otherwise the gluing of the felt with hot glue or other suitable adhesives requires a very special quality control.

The adhesive bonding of stamping felt parts on furniture glides made of Polyethylene or Polypropylene is only possible after a surface treatment or with special adhesives (cause of the unipolar surface of polyolefins). Usually this is disproportionately laborious and not recommended.

The durability of the felt on furniture glides depends only on the strain. The more the felt protrude from the furniture glide the more the felt is scraped off laminary in layers during shear stressing (cause of the marginal three-dimensional entanglement). On the other hand there is the wish to wear depth in order to extend the useful life up to the wear of the felt.

According to experience the compromise is that the felt protrude 2 - 5 mm from the furniture glide; but only on particularly sensitive floors that are dry cleaned regularly and if it can be expected that the user of the furniture handle cautiously with the furniture.

If the felt is too soft (low density) it is scraped off in layers after a short period of use or it wear out quickly. If the felt is too hard (high density) the contact surface (adhesive surface, welding area, moulding area) is more heafily loaded due to the lack of buffering effect during shear and impact stress. The felt starts to rub soft floors (marble, etc.) and the silencing can decline appreciably.

Legal notice
This article has been written and researched in good faith. However, the views and recommendations of Plasticmetall GmbH
presented here are for informational purposes only and are in no way legally binding; Plasticmetall GmbH is not liable for any possible damages arising from their implementation in practice.