Wood Screws in Furniture Making: PZ (Pozidriv) vs PH (Phillips) Compared

May 30, 2026

The main difference between PH (Phillips) and PZ (Pozidriv) lies in torque transmission: Pozidriv features additional ribs in the cross recess, preventing the bit from slipping out and enabling significantly higher torque in furniture making.

Choosing the correct screw drive during furniture assembly is essential for a clean and stable joint. When installing hinges, drawer runners, or carcase components, the profile in the screw head determines how much force the fitter can apply without damaging the material. A bit must engage with the screw head like a precisely cut key in a security lock. If the tool does not accurately fit the profile of the wood screws and furniture screws, wear and tear is inevitable.

Alongside the TX drive, two classic cross-recess variants dominate furniture construction: Phillips (PH) and Pozidriv (PZ). Although they appear identical at first glance, they are based on completely different mechanical principles.

What is the PH Drive (Phillips)?

The Phillips drive is the original cross-recess design. It was developed in the 1930s to overcome the disadvantages of the simple slotted drive in automated manufacturing. The profile consists of a simple cross.

The key technical characteristic of the PH drive is its flank geometry: the four flanks taper downwards. They converge towards the centre of the screw in a wedge shape. This design was historically intentional. Under high resistance, it causes the so-called cam-out effect. This means that the bit is automatically pushed out of the screw head once a certain torque is reached. In early industrial assembly, this prevented overtightening of the screw or shearing of the screw head when modern torque clutches on cordless screwdrivers did not yet exist.

For delicate work or fittings that do not require extreme force, small sizes such as wood screws PH1 are often used. For standard connections in furniture assembly, the size wood screws PH2 is more frequently employed.

What is the PZ Drive (Pozidriv)?

The Pozidriv drive is the technical evolution of the Phillips system, designed for higher torque transmission. A cross forms the foundation here as well, but with a crucial modification.

With the PZ drive, the four main flanks run parallel to one another and do not taper downwards. In addition, four smaller, offset ribs are machined between the main flanks. Visually, this creates a star pattern on the screw head. Thanks to the parallel flanks, the cam-out effect is virtually eliminated. The bit is not forced out of the screw as torque increases. The installer needs to apply less axial contact pressure to drive the screw into the material.

This is particularly advantageous with hard materials such as coated chipboard, dense MDF, or solid timber. For small fittings, tradespeople typically opt for wood screws PZ1, whereas for load-bearing carcase connections, wood screws PZ2 are the absolute standard.

Differences Between PZ and PH in Detail

To make the right choice when installing furniture fittings, the technical differences can be summarised in the following points:

Flank geometry: PH flanks are wedge-shaped (conical), whilst PZ flanks are parallel.
Torque transmission: PZ allows for significantly higher torque than PH, as the force acts perpendicular to the parallel flanks.
Contact pressure: With PH screws, the user must press firmly against the screw to prevent cam-out. With PZ screws, moderate pressure is sufficient, as the bit self-centres and holds securely due to the parallel flanks.
Visual identification: PH features a simple, smooth cross. PZ features a cross with four additional fine lines at a 45-degree angle (a star-like appearance).
Wear and tear: When used correctly, wear on both the bit and the screw head is significantly lower with PZ systems.

When to Use PZ and When to Use PH?

The choice of drive depends heavily on the fitting being installed and the base material.

Areas of Application for PZ (Pozidriv)

The PZ drive is the primary choice for structural furniture assembly. When joining thick chipboard panels or securing fittings that must carry heavy loads permanently, Pozidriv is mechanically superior. Typical applications include mounting hinge plates, screwing full-extension runners to carcase sides, or fixing adjustable furniture feet.

For standard furniture fittings, screws with a diameter of 3.5 mm or 4 mm are generally used. Corresponding wood screws 4mm or wood screws 3.5mm, combined with the PZ2 drive, provide optimum hold in timber-based materials.

Areas of Application for PH (Phillips)

Today, the PH drive is still frequently found in imported flat-pack items, drywall screws, or small decorative fittings that do not require high torque. Manufacturers also often utilise a PH profile for hinge adjustments (adjustment screws for gap alignment and depth on concealed hinges), as only minimal force is needed for setting them.

Specialist fitting hardware such as connecting bolts, which are used to join two carcases (e.g. in kitchen cabinets), often feature a PH or PZ drive depending on the manufacturer, as they are usually inserted into pre-drilled holes and merely tightened moderately. If fittings are to be mounted on dark furniture, black wood screws are chosen for aesthetic reasons; here, too, the drive profile must match the tool precisely to prevent the black coating from chipping due to slipping bits.

What Happens When Using the Wrong Bit?

A common mistake during furniture assembly is mixing PH and PZ components. Because the bits look similar at first glance, they are often swapped by accident. This leads to immediate mechanical consequences:

PZ bit in a PH screw: The PZ bit has additional ribs that cannot fit into the simple cross-recess profile of the PH screw. The bit cannot seat deeply enough into the screw head. It wobbles, tilts, and strips the edges of the screw head on the very first turn.

PH bit in a PZ screw: The PH bit fits deep into the PZ screw, but due to its wedge shape, it has excessive play within the parallel flanks of the PZ head. As soon as force is applied, the bit engages only at specific points. The result is an immediate cam-out effect: the bit slips, rounds off the screw head, and ruins the screw.

Frequently Asked Questions (FAQ)

How can I instantly tell whether I have a PZ or PH screw?

The most reliable visual indicator is the presence of four additional fine lines on the head of a PZ screw. These radiate outward in a star shape between the main cross recesses. If these lines are missing and the screw head shows only a simple, smooth cross, it is a PH screw.

Which screw size and drive do I need for concealed cup hinges?

To fasten standard furniture hinges and mounting plates in the System 32 grid, chipboard screws with a diameter of 3.5 mm or 4 mm and a length of 16 mm are generally used. The PZ2 drive is the absolute industry standard here, providing the necessary torque for a secure grip in timber-based materials.

Can I use Torx (TX) instead of Pozidriv (PZ) for furniture making?

Yes. The Torx drive (hexalobular) is the most modern variant and transmits force even more effectively than PZ, as it requires zero axial contact pressure. While PZ continues to dominate standard hardware fitting assembly (hinges, runners), TX is increasingly used for structural carcase assembly and long construction screws.

Why are my screws spinning freely when driven into chipboard?

If the screw spins without gripping, either the cam-out effect has occurred (the wrong bit was used, e.g. PH on PZ), or the screw was overtightened and the thread has stripped the core of the chipboard. In the latter case, plugging the hole with a wooden dowel or switching to a screw with a larger diameter will restore the fixing.