Choosing the right screw

Fixing screws are mechanical elements that allow several parts to be fixed together. They make it possible to assemble parts that can then be easily dismantled. Many people confuse screws with bolts. They are both fastening and joining elements: a screw is a threaded rod while a bolt is the set formed by a screw and a nut.

It is important to distinguish between fixing screws and power screws (also known as lead screws), which are one of the components of a ball screw (mechanical transmission element) and which we will not discuss in this guide.

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  • How to choose a screw?

    The first factor that will guide your choice of screw is the material it will be screwed into. There are many different types of screws, each corresponding to the material they will be used for. There are screws for concrete, wood, PVC, plaster, etc. Each type of screw has its own characteristics and is optimized for use with a specific material.

    You will then have to choose your screws according to their length and diameter. These elements are essential because they determine both the strength of the screw, but also whether it is truly adapted to your needs.

    Before buying screws, we recommend that you make sure you have the right screwdriver or drill bit. Some screws have special shapes and therefore require the use of an adapted tool.

    We also recommend that you pay attention to the thread that runs the length of the screw shaft. The screw can be threaded along its entire length or only on a part of the shaft.

    The material of the screw is not something to be taken lightly. It is essential to choose a screw that is resistant enough for the environment in which it will be used.

  • What are the main types of screws?

    There are several types of screws. Depending on your intended use, you can choose from:

    Wood screws: these are used for screwing into wood. They are usually made of zinc or stainless steel and have a small diameter. They have a slotted button head. Wood screws usually have a partial thread.

    Wood and chipboard screws: these are usually made of zinc or stainless steel. They are small and very sharp, their thread runs the entire length of the shaft. Their head is countersunk, with either a Pozidriv (cruciform) or Torx (six-point) drive type. Their main advantage is that they are self-drilling and allow you to screw into wood without splitting it or having to pre-drill.

    Drywall screws: these screws are generally long and extremely sharp. They are black and their thread runs the entire length of the shaft. They have a countersunk Philips head.

    Metal screws: these screws are are available in different materials, steel being the most common. They are designed to be used in pre-tapped holes. Their lengths, head shapes and drive types are diverse and varied. These screws are often used when a screw head is needed that fits into the bracket. They are very strong and resist high temperatures, shearing and tearing.

    Sheet metal screws: these screws are particularly resistant. There are three models available: pointed end (for thin sheets), rounded end and flat end (for thick sheets). These screws have a thread similar to that of wood and chipboard screws, so be careful not to confuse them! They can have a button, countersunk or cylindrical head, usually with a Pozidriv or Torx drive type.

    Concrete screws: these screws come in several materials, lengths, head shapes and drive types. However, concrete screws can be recognized by their very large thread. They are very resistant and do not necessarily require the use of a plug. It is advisable however to do preliminary drilling before screwing them in.

    PVC screws: these screws are generally made of stainless steel and have a countersunk head and Torx drive type. Their thread is very thin and allows them to be screwed in without using a plug.

    Lag screws: these screws are made of zinc or stainless steel. They come in various lengths with a partial thread and hexagonal head. They are very resistant to being torn out. They have a pointed tip that allows them to easily sink into the material.

    Self-drilling screws: these screws are capable of drilling through soft metals, thin sheet metal and plastic with their drill-bit-like tip. They can have a countersunk, hexagonal or button head, with a Phillips, Pozidriv or hexagonal drive type. Self-drilling screws are often used in the construction and automotive industries.

  • How to choose a screw head?

    Why is it important to take into account the screw head?

    It is first important because, depending on your application, you may need a screw with a head that penetrates the material completely, or conversely, that protrudes from the material.

    Secondly, because some screws are used to assemble large parts, it is important to choose a screw head that will not loosen easily to hold the assembly in place.

    You can choose from the following screw heads:

    • Hexagonal screw heads: these screws are more difficult to fasten than the others and require the use of an Allen key screwdriver or hex drill bit.
    • Square screw heads: these are flat screw heads that allow the user to screw them in easily with one hand.
    • Countersunk screw heads: these screws are generally used in wood or plaster. They are fully integrated into the material and are often favored in carpentry.
    • Button screw heads: these screws have the same advantages as countersunk screws. They are also equipped with a washer that remains on the surface.
    • Cylindrical screw heads: these are recognizable by the flat underside of the head which ensures better surface contact.
  • How to choose a screw drive type?

    Now that you have determined the head you need, you can turn your attention to your screw’s drive type. Remember to check the compatibility of your tools with the screw drive type you are planning on choosing.

    Here are the most commonly used drive types for screws:

    Slotted: this extremely simple drive type has the disadvantage of not offering centering of the tip. As a result, the screwdriver slips easily on a slotted screw.

    Phillips: this drive type allows you to center the screwdriver tip so it does not slip. This is known as a Phillips or cruciform screw. This greater maneuverability makes the user’s work faster and more efficient, whether they are using a manuel or electric screwdriver.

    Pozidriv: this is an improved Phillips drive. Its two crosses give the screwdriver better stability. We recommend that you avoid using a Phillips drive tool with a Pozidriv screw, or vice versa, as this will damage the tool and/or the screw, whether you are using a manuel or electric screwdriver.

    Pentalobe: these screws will protect you from the slipping of the screwdriver more than Phillips screws. They are often used in electronic products such as computers, tablets and cell phones. They can be screwed in faster and more efficiently.

    Torx: like the Pozidriv drive type, the Torx provides very high stability to the tool, preventing the screwdriver from slipping. Its rounded points ensure that neither the tool nor the screw is damaged, thus prolonging the service life of both.

  • How to choose the material of a screw?

    Screws are designed to be made of materials that are suitable for their intended use.

    • Zinc-coated steel screws: these screws have a zinc coating that allows them to be moderately corrosion resistant. They are silver in color. Wood screws, chipboard screws and lag screws are generally zinc-coated.
    • Dichromate screws: these screws also have a surface treatment that protects them from corrosion. This treatment can quickly disappear for this type of screw. They are yellow in color. Wood and chipboard screws are often dichromate.
    • Phosphate screws: These screws are very resistant and protected against corrosion. They are black in color. Drywall screws are generally phosphate.
    • Chrome-plated screws: these screws are very similar to zinc-plated screws and have the same resistance characteristics.
    • Brass screws: these screws have not been treated and are therefore very sensitive to corrosion. A corroded brass screw shows verdigris. For this reason, we suggest you only use them indoors. They are gold in color and generally used in cabinet-making.
    • Stainless steel screws: these screws are very resistant and rustproof. This means they are optimized for outdoor use. Two models are available: A2 stainless steel screws which have good resistance to corrosion under normal atmospheric conditions and A4 stainless steel screws which also protect the screw against acids. They are gray in color. Wood and chipboard screws as well as PVC screws can be made of stainless steel.
  • Why choose a self-tapping screw?

    Self-tapping screws allow you to tap a hole directly. This eliminates the need to use a tap, thus reducing costs. Self-tapping screws are also very strong and have excellent holding power. They are resistant to tearing and vibrations. Self-tapping screws are designed to be used with all types of materials (wood, steel, metal, etc.). They are used in many fields and applications such as sheet metal, bodywork and profiles. These screws will save you time and money.

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