Spax has a handy glossary they have written as a guide to some of the terminology used for their screws and accessories:
Austenite stainless steel – the main microstructure component of many stainless steels. It is non-magnetic. Austenitic stainless steel has a higher corrosion resistance than martensitic steel.
Antique screws are made of stainless steel whose colouring was achieved by thermal processing. The use of stainless steel for these screws makes them highly corrosion-resistant. This allows for their use outdoors. Antique screws appear brownish, thus, they are excellently suited for applications in terrace and facade construction using dark wood.
A BIT is a small interchangeable screwdriver tip without a handle. These are available in many different designs for every conceivable recess shape. The BITs are typically magnetic, and thanks to their hexagonal shape can easily be inserted into the bit holder. There is thus no need to carry around many different screwdrivers, and the appropriate tool is nevertheless always available. To accompany the SPAX product range with the SPAX T-STAR plus recess, they offer SPAX BITs T-STAR plus with colour coding, precisely fitting our screws. These are available in bit sizes T10 to T40. Using SPAX BITs T-STAR plus, you achieve a better transmission of energy, longer service life, faster insertion and a better fit. In addition, the colour coding results in faster access.
Brass Coated – The application of a brass alloy avoids manufacturing from brass, and hence fulfils the aesthetic requirements while retaining the familiar screw properties. Screws made from pure brass would not fulfil Spax’s quality requirements, as brass is too soft as a material. Whether a screw is brass-plated or made from brass can be tested using a magnet: brass-plated = magnetic / brass = non-magnetic. Spax recommends these are only used indoors.
Bronze Finish – screws with a bronze finish are made of steel whose surface was improved by chemical processing. Compared to galvanized screws, their surface is less corrosion-resistant and should only be used indoors. Screws with a bronze finish appear brownish, thus, they are excellently suited for applications in furniture restoration with dark or antique woods.
Bulk Density – The gross density determines the dead-weight load of the construction material. Wood contains varying proportions of water, depending on whether the timber is freshly cut, has dried somewhat since being cut, or whether it has been dried to wood equilibrium moisture content for indoor use. Wet wood is the heaviest here. As the mass of the wood is dependent on the water content of the wood, the gross density value is dependent on the wood moisture content. The gross density is indicative of the ratio of cell wall material to hollow space in the wood. It is a ratio value that needs to be calculated. The gross density “p” of wood and timber products is the ratio of the mass “m” to its volume “v”. Gross density = mass of the wood / volume of the wood = kg/m³ Examples based on a wood density of 12%-15%: balsa wood 90-260 kg/m³, spruce 330-680 kg/m³, bangkirai 900-1,100 kg/m³, Ip³ 960-1,900 kg/m³ (ironwood) The range of the gross density is also dependent on the location-specific and environmental factors affecting the wood, e.g. the source of the tree (e.g. Asian continent). The differences in gross density within a wood type can be seen from the respective differences in the width of the growth rings in the wood.
Cam Out Effect – With conventional, conical recesses such as the cross recess, there is always the problem that the torque applied by the user will force the screwdriver bit upwards and out of the recess. This often results in the bit slipping out, or even in the total destruction of the recess (we also say the screw has been “stripped”). In order to counter this slipping effect, the user needs to apply contact pressure. The use of a recess with a parallel profile (e.g. the SPAX T-STAR or the SPAX T-STAR plus) avoids the undesired cam-out-effect and the need to apply contact pressure. “Stripped screws” are hence a thing of the past.
Centre Drill – The head access drill hole is the pin-shaped depression inside the screw head that connects to the recess. This drill hole allows special cover caps for this type of screw to stay in place particularly well, and secures them against falling out.
Corrosion – Corrosion (from the Latin word corrodere = “to gnaw away”) is the reaction of a material with its environment. Corrosion occurs in metals, for example, and causes a measurable alteration in the material, resulting in an impairment of the functionality of the component. The most familiar form of corrosion is rusting, i.e. the oxidation of iron. Corrosion resistance is the degree of protection against rusting.
Countersunk Head – The countersunk head is the most commonly used screw head geometry. It has a conical form and is characterised in the case of SPAX by the 90° SPAX MULTI Head. It can be optimally inserted into wood materials, and closes flush with the surface.
Cover Caps – The practical cover caps make unattractive screw heads disappear in a flash. Simply insert the appropriate cover cap into the recess in the screw head, and the screwed connection becomes virtually invisible. Our range of products covers most conventional surface colours. The following types of cover caps are available in the SPAX product range: A) caps for head access drill holes B) caps for SPAX T-STAR plus C) caps for Pozi D) caps for SPAX-RA
Cross recess, type H (Phillips) – By contrast to the simple slot recess, the cross recess developed by Phillips the risk of the tool bit slipping out of the recess sideways and damaging the workpiece. As the flanks in the cross recess are tapered, however, strong tightening of the screw produces an axial force that pushes the bit out of the recess (Cam-out effect). This recess is used in screws for windows (FEX).
Cross recess, type Z (Pozi) – This recess, also known as the double-cross, is a further development of the recess designed by Phillips. The difference lies in the fact that the four flanks of the screwdriver bit do no taper towards the tip. This reduces the cam-out effect somewhat. For this reason, the cross recess Z is a recess frequently used at SPAX.
Cylindric head – The SPAX with cylinder head can easily be sunk into wood, and thanks to the small head diameter results in an almost invisible screwed connection. The reduced splitting effect when sinking the head makes SPAX with cylinder heads particularly popular in timber construction and terracing applications.
Drill Point – Screws with drill points are shaped like a drill at their tip. The resultant independent cutting effect offers optimal drilling into metal, both during manual work and when using a screwdriver machine. Screws with these drill points are particularly well suited for attaching fittings to window profiles with metal reinforcements.
Driving Torque – The screwing-in torque is the term for the force that is required in order to screw the screw into the base material. The screwing-in torque can be reduced and non-tiring work hence facilitated by means of special coatings, pre-drilling, or naturally through the key characteristics of our SPAX, the SPAX ground serrations, the SPAX 4CUT cutter and the SPAX 4CUT point.
Fex – FEX-A The window construction self-drilling screw. For fastening single-wall UPVC profiles. FEX-KS Countersunk head-fitting screw – For fastening fixtures to plastic profiles FEX-RS The shutter screw – For snap-on head fastening of roller shutter guides FEX The fixture screw – With SPAX CUT point FEX-H The screw for wooden window frames – For fastening fittings to wooden window frames
Fixing thread – The fixing thread is a second thread immediately below the head of the SPAX. The fixing thread guarantees a secure and permanent connection of two wood components. In particular when laying wooden flooring indoors using the SPAX flooring screw, or when building a wooden deck outdoors using stainless steel SPAX-D, the fixing thread holds the cover board permanently onto the substructure. This thus minimises creaking from the floor structure.
Flange head – The flange head is a flat overlying head that is commonly used in the furniture industry to attach hard fibreboards to the rear of cabinets and storage racks. The flat, washer-like head of the screw is space-saving, and enlarges the contact surface on the fibreboard. The head cannot easily be pulled through the wood board. The flange head is available in the SPAX product range up to an outer thread diameter of 5.0 mm.
Galvanic corrosion – Contact corrosion can occur when different high-quality metals are in close contact with one another. For example, if a stainless steel screw is screwed into a zinc-plated steel sheet. The higher-grade metal then promotes corrosion (rusting). This results in what is known as contact corrosion. This process requires a corrosive medium between the two metals, for example water, or simply normal humidity.
Galvanization – passivation – synthetic coating – A) Zinc yellow passivated B) Zinc-plated, transparent passivated (generally termed “bright galvanised, zinc-plated”)
- The application of a zinc layer protects the material of the screw from corrosion and simultaneously gives it a greyish, silver-coloured appearance.
- The application of a passivation layer to the zinc-plated surface of a screw results (depending on the chemical process used) in a yellowish or transparent coloration of the metal. The passivation of the zinc layer improves the corrosion protection.
- After the zinc coating and passivating processes, the screws are given a further synthetic coating, which reduces the screwing-in torque required, making the screws easier to use. SPAX with zinc-plated surfaces are for indoor use. They should not be used outdoors or in damp locations.
Glass strip – The glazing bead is the strip on a sash window that holds and supports the pane of glass. In the event of damage to the glass, this strip can easily be removed in order to replace the glass.
Head shapes – Flat countersunk head, SPAX MULTI Head, Flange head, Washer head, With centre drill, Cylindric head
Hexagonal socket – A hexagon socket does not have a recess for a screwdriver bit, and is tightened using an open-ended or ring wrench, or an appropriate box nut. This head shape can be found in SPAX threaded rods.
MDF – The term MDF is the short form of the term “medium density fibreboard”. The name derives from the fact that the density of these plates lies between that of timber and that of high-density fibreboard (HDF). MDF boards are used in interior construction and attic conversions. In addition to cupboards and cabinet systems, MDF boards have for a number of years been used in powder-coated form as table and cover boards. Their high flexibility and tensile strength also make them popular in building high-quality speaker systems. MDF can be treated with many kinds of paint and other coatings, creating a smooth, clean surface with profiled edges, cutouts etc.
Milled ribs – Milling ribs are small, wedge-shaped ridges under the countersunk head of the SPAX. As soon as the head of the screw meets the wood, the milling ribs go to work: this facilitates flush and clean countersinking of the head.
Nickel coated – The application of a nickel alloy protects the material of the screw from corrosion and simultaneously gives it a chrome-coloured, slightly yellowish appearance. We recommend these are only used indoors.
OSB – OSB means “oriented strand (or structural) board”, and refers to a board manufactured from wood material and consisting of long strips running in the same direction. OSB boards are widely used in the construction industry, e.g. for wall, ceiling and floor planking. The length of the strands is the reason for the flexibility and strength relative to normal compressed boards (chipboard).
Partial thread – The partial thread only extends over part of the length of the screw. Screws with partial thread are particularly suitable for attaching wooden boards to wooden beams. The non-threaded part should always be selected such that it corresponds to at least the thickness of the board to be screwed into place. The thread tightens securely into the lower piece of wood, while the upper piece of wood is held tightly against the lower by the screw head. For SPAX screws up to 100 mm in length the following rule of thumb can be used for calculating the screw length required for connecting two pieces of wood, e.g. in deck construction: The screw length (Ls) is derived from the thickness of the cover board (t). Formula: Ls = 2.5 x t Example: Ls = 2.5 x 24 mm => Ls = 60 mm
Phosphoric – Phosphate treatment is a process that is generally used with steel. This is generally understood to mean the application of a well adhering phosphate layer. Phosphate-treated screws (GIX) are predominantly used in dry walling (drywall or fibre-reinforced plasterboard). Zinc-plated screws are not compatible with the plaster putty used in dry walling.
Point shapes – SPAX 4CUT point, SPAX CUT point, Drill point
Pre-Drilling – Pre-drilling means to drill a hole in a workpiece, which should have a smaller diameter than the screw. The pre-drilling creates space for the screw in the material and hence prevents the workpiece from splitting. Pre-drilling is a time-intensive work stage, which can effectively be dispensed with through the use of SPAX with SPAX ground serrations and SPAX 4CUT point (wood-dependent). The tedious pre-drilling can be dispensed with (wood-dependent), as the special SPAX 4CUT point cleanly displaces the fibres of the wood and hence prevents splintering and splitting of the wood, even with small distances from the edge. It should be noted that pre-drilling is always recommended for very hard woods. Pre-drilling diameter for SPAX in softwood and hardwood:
- * not currently regulated by national technical approval ** not customary in Germany
- Softwood: fir, spruce, larch, pine, Douglas fir
- Hardwood: oak, beech
Pull-out forces – The pull-out strength means the force that would have to be applied to tear the screw out of its anchoring. It is dependent on multiple factors, e.g. screw geometry, screwing-in depth, material used, thread length etc.
Recesses – BIT, Cross recess H (Phillips), Cross recess Z (Pozi), SPAX T-STAR, SPAX T-STAR plus, Hex. socket
Restraining ribs – Restraining ribs are small, wedge-shaped ridges under the countersunk head. These act as brakes for the screw when placing on a metal fitting. This effectively prevents over-screwing the screw, and creates a solid connection between the metal fitting and the component.
SPAX – The letters of the SPAX brand name stand for the German meaning “chipboard screw with cross recess ()“. SPAX were marketed for the first time in 1967, and have since developed into a world-famous brand product of the highest quality, Made in Germany. SPAX are now available in many different designs as universal screws, and as special screws for a wide variety of applications.
SPAX 4CUT cutter – The square characteristic of a SPAX at the transition from the thread to the shaft is referred to as a SPAX 4CUT cutter. This has the advantage of reducing the torque required for screwing in by up to 60%. The SPAX can thus be used evenly and without the use of much force; this also saves the energy reserves of a battery-powered tool. The SPAX 4CUT cutter is generally used for screws exceeding 160 mm in length.
SPAX CUT point – The SPAX CUT point is distinguished by its arrow shape, and can be placed precisely. The special screw geometry effectively reduces splitting of the wood or the timber product (e.g. MDF). For very hard wood types, we recommend pre-drilling even for SPAX with CUT point.
SPAX ground serrations – The advantage of a thread with SPAX ground serrations as opposed to a conventional thread is that it can cut through the fibres of the material more easily. This functions similarly to a serrated knife, which offers the same advantages e.g. when cutting a tomato. The SPAX ground serrations on the thread of the SPAX, in combination with the SPAX 4CUT point allow use without pre-drilling (wood-dependent)!
SPAX MULTI head – Mills into wood – brakes on metal. The SPAX MULTI Head has recessed pocket segments. Edges are thus formed between the individual segments, which reveal their cutting effect when they come into contact with wood. The head is thus countersunk cleanly and flush. If a SPAX with SPAX MULTI Head is used for attaching a metal fitting, the non-recessed surfaces of the screw stop when they come into contact with the metal fitting. This effectively prevents over-screwing the screw, and creates a solid connection between the metal fitting and the component. The surfaces are not damaged.
SPAX T-STAR – The driving surfaces of SPAX T-STAR recess are arranged in the shape of a star and run vertically, simplifying the insertion of the tool and ensuring a solid grip. No cam-out effect occurs with this form of recess. The contact pressure force for screwing-in is reduced to a minimum, and high torques can be transmitted to the screw without this affecting the screw or the tool itself. In the SPAX product range, the diameters 10 mm and 12 mm have a SPAX T-STAR recess.
SPAX T-STAR plus – The SPAX T-STAR plus recess offers all the advantages of the SPAX T-STAR recess (no cam-out effect, minimises contact pressure force, accepts higher torques). In addition, this recess has a small depression in the screw head below the driving surface, into which the appropriate SPAX T-STAR plus BIT with guide cone can be inserted precisely. This SPAX T-STAR plus connection ensures optimal force transmission, a long service life for the SPAX T-STAR plus BITs, and a perfect fit. Even trouble-free overhead use of SPAX is possible, as the screw is guided considerably better, and can no longer fall off the BIT.
Stainless steel – SPAX made from stainless steel are particularly suitable for outdoor use. These are available in the stainless steel A2 design for outdoor applications directly exposed to the elements, as well as for use in humid indoor spaces (e.g. kitchen and bathroom). For applications in coastal areas, we recommend the stainless steel A4 design. Stainless steel is characterised by a high proportion of chromium. This results in the formation of a protective layer on the surface of the material. Other alloy components such as nickel, molybdenum, manganese and niobium result in even better corrosion resistance. Austenite is the main microstructure component of many stainless steels. It is non-magnetic. Austenitic stainless steel has a higher corrosion resistance than martensitic steel.
Surface – Galvanization–passivation–synthetic coating, Antique, Brass coated, Nickel coated, Phosphoric, WIROX
Thread forms – Partial thread, Fixing thread
Washer head – The washer-like head of the screw increases the contact surface with the workpiece, and hence guarantees considerably higher head traction forces relative to a countersunk head screw. The SPAX washer head allows improved tightening of the connection between the wooden parts. The washer head is available in the SPAX product range, starting at an outer thread diameter of 6.0 mm.
WIROX – The new WIROX coating of SPAX offers 10 times higher corrosion protection in the neutral salt-spray fog test than is required by standard for conventional yellow zinc coating, and has considerably higher surface hardness. This makes it ideal for outdoor use in structures such as e.g. carports or pergolas, which are not directly exposed to the elements. The WIROX coating is free from chromium-VI, and is hence considerably more environmentally friendly to manufacture and also to use than conventional surfaces. Attention: SPAX WIROX cannot replace SPAX stainless steel for outdoor applications.