STAINLESS STEEL SLOTTED SET SCREWS FLAT POINT DIN 551

Slotted Set Screws Flat Point DIN 551 — Where a cup point is designed to bite, a flat point set screw is designed not to: its flat, lightly chamfered tip bears against the shaft over a broad, even contact area rather than digging in, which makes it the natural choice wherever the shaft surface is finished, hardened, plated, or otherwise needs to stay unmarked. That gentler contact does come at a cost in raw holding power compared with a cup or cone point on the same shaft, so flat point set screws are typically specified for lighter clamping duties, adjustable collars and stops that are repositioned regularly, and instrument or precision equipment where preserving the shaft's surface finish matters as much as, or more than, maximum resistance to slipping. Grade selection is largely an environmental question here too: A2 covers most indoor machinery and instrument applications comfortably, while A4 is worth specifying for equipment exposed to washdown, marine air, or chemical processing environments, since a flat point's already-modest grip is further undermined if the screw itself starts to corrode and lose thread integrity. DIN 551 sets out the thread, point geometry and screwdriver slot for this fastener, and — being flat rather than shaped to bite or locate — the point profile is simpler to manufacture consistently than a cup or cone tip, which keeps this a cost-effective option where its lower holding power is acceptable. Choosing the right screw means matching diameter to the tapped hole in the collar and length to the wall thickness, ensuring the flat tip reaches the shaft cleanly without either falling short or bottoming out in the hole before making contact. If the assembly needs to be adjusted and repositioned repeatedly without leaving cumulative damage on the shaft, flat point is generally the right call; if maximum resistance to slipping is the priority and marking the shaft is acceptable, a cup or cone point set screw will outperform it.

FAQs
Does a flat point set screw need to be re-tightened more often than a cup point?
It can, in higher-vibration or heavier-load applications, since it relies on friction alone rather than a mechanical bite; for settings where repeated loosening is a concern but the shaft still can't be marked, adding a thread-locking compound is a common compromise.

Is flat point suitable for hollow or thin-walled shafts?
It's generally a safer choice than cup or cone points here, since it doesn't concentrate force into a small indentation that could distort a thin-walled tube; even so, torque should be kept moderate on thin sections regardless of point type.

Can a flat point set screw be used on a shaft with an existing dimple for a cone point?
It's not ideal — the flat face won't seat into the dimple the way a cone point does, leaving reduced and uneven contact; if the shaft already has a locating dimple, a cone point set screw is the better match.

What torque should be applied to a flat point set screw?
There's no universal figure, since it depends on screw size, material, and the clamping duty; because flat point relies entirely on friction, applying manufacturer-recommended torque for the specific size is more important here than with a biting or locating point type.