Screw Drive Types

What a drive has to deliver

The drive recess is an assembly-line variable before it is anything else. On a production line the drive determines which bit the operator loads, how fast the tool can run, how much torque the joint sees, and how often the bit is replaced. Choosing a drive because you like the look of it is a mistake — the drive has to be chosen against the torque, access, cycle rate and service life of the joint.

The table below lists the fifteen drive styles we most often produce. The useful distinction is between two jobs: a drive that transfers torque efficiently and repeats thousands of times, and one that is cheap to produce and forgiving on a line where conditions are imperfect. Those two jobs rarely point to the same recess.

Cam-out and why it matters in production

Cam-out is when the driver bit climbs out of the recess under load instead of turning the screw. It is usually read as a defect — a rounded recess, a stripped bit, a scratched part — but the cross-head screw was actually designed to do it, and knowing why changes how you read a specification.

Phillips was designed so that, past a set torque, the bit would deliberately ride up out of the recess rather than over-torque the screw. In the era of the torque-limiting screwdriver this made sense: the recess itself was the limiter. Today, with powered tools and preset torque, cam-out is mostly unwanted — it wears bits, rounds heads and slows the line — but a self-limiting recess still helps when a screw must not be over-driven into a fragile assembly. Match the drive to the tooling: a recess that cams out at the wrong torque is the wrong recess for that line.

Cross recesses: Phillips, Pozidriv and JIS

The three cross recesses look almost identical and are not interchangeable. Phillips has a tapered centre and angled flanks that intentionally push the bit out under load. Pozidriv adds a second, smaller cross at 45°, and — the detail that causes most of the damage — its flanks are parallel, not tapered. A Phillips bit in a Pozidriv screw engages poorly and cams out; a Pozidriv bit in a Phillips screw sits too deep and rounds the recess. They must not be mixed up, and a drawing callout has to name the exact recess or the shop will guess.

JIS (Japanese Industrial Standard) cross is the third one that gets confused. It looks close to Phillips, but the recess is shallower and does not cam out the way a Phillips driver does, which matters on older Japanese automotive and electrical products. Using a Phillips bit on a JIS screw is the classic way to strip it. Name the recess precisely on the drawing, because the three are produced with different punches and cannot be corrected after the fact. See custom screws for a specific cross recess.

Internal drives: hex socket and Torx

Hex socket and Torx are the two internal drives for high torque where the tool engages from above. A hex socket (Allen) drive is simple and cheap to produce and self-centring enough for hand work, but its six corners round quickly when the bit is worn or the angle is off. Torx and Torx Plus are built for higher torque: the star geometry spreads the load across six lobes with near-vertical drive faces, so the bit stays engaged where a hex would cam out.

That difference drives the specification. On a socket head cap screw tightened once with a calibrated tool, hex socket is fine; on a line where the same joint is driven thousands of times a day, Torx pays for itself in bit life and fewer stripped heads. Twelve-point and spline extend the same logic to external engagement: the twelve-point internal wrenching head is standard in aerospace and high-performance automotive work because a thin-walled socket reaches a tight counterbore at high torque, and spline gives similar capacity with less chance of rounding.

Tamper-resistant drives

Tamper-resistant drives add a step to removal rather than preventing it. A pin-in-hex, pin-in-Torx or one-way (clutch) head installs with standard or near-standard tooling but needs a matching security bit — or destructive force — to remove. The honest description is that these are deterrents, not locks: they stop casual or opportunistic disassembly, and they are common where a manufacturer wants to keep end users out of an enclosure.

The limits matter when you specify them. Most security recesses are not meaningfully stronger than their standard equivalent, and a determined user with the matching bit will remove them anyway. Choose a security recess only where the deterrent value is real and the service environment tolerates the harder rework of a legitimate repair. We produce the common security forms and can machine a proprietary recess to drawing where a standard security bit is not enough.

Drives we can produce and how the recess is made

How a recess is produced determines both its cost and its minimum quantity. The recess is created one of three ways: formed into the head during cold heading or forging, broached, or machined. A formed recess is the lowest-cost route at volume because the punch does the work in the same stroke that makes the head, but it commits you to a tool — fine at tens of thousands of pieces, uneconomical for a short run. Broaching cuts the recess after the head is formed and suits recurring mid-volume runs. Machining the recess on a mill is the flexible route: it makes small quantities and one-off sizes practical, because no dedicated punch or broach is needed.

That flexibility is the point for a buyer working from a drawing. When the catalogue recess does not match your tooling or torque target, we machine it to your specification — samples from one piece, production from 50 pieces, quotes within 24 hours with DFM feedback on the geometry. The recess dimension is a tolerance-controlled feature, held to ±0.01 mm where it locates the driver. Send the drawing through request a quote, and pair this page with the fastener head types reference when choosing the head and drive together.