What should I determine first when selecting a drill point die?

Start with the thickest substrate the screw must penetrate — this sets the L-series (flute length). Thickness narrows the field to a few candidate series; your screw size then converges on a specific die code, because flute length also scales with screw size. Material and coating come last and depend on screw material and volume, not first.

How do I choose between MA, MB and MC die styles?

By screw size: IFI #8 and below typically use MA (Style I), #10–#12 use MB (Style II), and #14 and above use MC (Style III). The L6 and L7 series are MC only. Style determines the die's overall body dimensions and must match your header's die pocket, so confirm your machine model when requesting a quote.

What changes when producing stainless steel self-drilling screws?

For 304 and 316, carbide dies are recommended — HSS life in stainless production is typically much shorter. On coatings, 304 commonly uses CrN to suppress galling (adhesive wear), while 316 work-hardens more aggressively and generally calls for AlCrN. For carbon steel screws both HSS and carbide are workable and coating is optional, traded off against volume.

Can I request a quote without complete drawings?

Yes. In practice the three most common starting points are an existing screw sample, the old die itself or photos of it, and a trial-run video of the finished screw. Screw size (IFI number or DIN ST value), drill diameter, target substrate thickness and screw material are usually enough to narrow down candidate die codes.

Drill Point Die Selection Guide: Five Steps to the Right Series, Style and Material

The cost of picking the wrong drill point die is rarely the die itself — it is the line. Screws that will not drill through, chipped points, dimensions drifting out of tolerance, scrap climbing. A die costing a few hundred dollars can take out a full shift of output.

This guide breaks selection into five steps, in the order the decision actually gets made during an RFQ. It is written as a procurement and process reference rather than a technical white paper: each step gives you something you can act on, plus what to ask when you cannot decide.

Step 1: Establish the screw standard and size

First, pin down which standard you are working to — it governs how every parameter downstream is expressed.

IFI (North American system) uses numbers #4 through #14
DIN 7504 (European system) uses nominal diameters ST2.9 through ST6.3

The approximate cross-reference:

IFI	#4	#6	#7	#8	#10	#12	#14
DIN	ST2.9	ST3.5	ST3.9	ST4.2	ST4.8	ST5.5	ST6.3

This is an approximate conversion, not an equivalence. The two standards differ in tolerance bands, test methods and material requirements. For export orders, produce to the standard of the destination market rather than ordering against a converted value.

The entry most often gotten wrong is IFI #7 — it maps to DIN ST3.9, not ST3.8.

Step 2: Size the L-series by substrate thickness

The L-series determines the flute length (ℓ) of the drill point. Longer flutes penetrate thicker material. Size against the thickest material the screw must go through, not the average.

Substrate thickness	Candidate L-series	Typical application
< 1.0 mm	L1	Thin sheet metal, HVAC ducting
1.0–2.0 mm	L1–L2	Light-gauge steel framing
2.0–4.0 mm	L2–L3	Medium-gauge construction
4.0–8.0 mm	L3–L5	Heavy-gauge steel
8.0–12.0 mm	L5–L6	Structural steel
> 12.0 mm	L6–L7	Extra-thick structural steel

Why does one thickness map to several series? Because flute length also scales with screw size — a #8 and a #14 screw going through the same 4 mm plate fall into different series. Thickness only narrows the candidates; converging on a specific code takes the screw size from Step 3.

Both directions cause problems. Too short, and the threads engage before the point has drilled through — the screw stalls and the hole is incomplete. Too long, and you waste material while adding spin-down time at assembly, which is what installers mean when they complain a screw "takes forever to bite."

Drill Point Die Selector

Enter screw size and plate thickness to get the matching die code

Open the selector tool

Step 3: Set the die style by screw size

Die style determines the overall body dimensions of the die, which decides whether it fits your header at all.

MA (Style I) — smaller screws, IFI #8 and below
MB (Style II) — #10 through #12, the most widely used style
MC (Style III) — #14 and above

Note that the L6 and L7 series are offered in MC only, while L1 through L3 may be MA or MB in the smaller sizes depending on the specific drill diameter.

Style has to match your machine's die pocket. This is the item most often left out of an RFQ: for the same #10 screw, die pocket dimensions can differ between header brands. If you are unsure, give the header model directly, or measure the die you are currently running and send the dimensions.

Step 4: Choose die material by screw material

This step trades die life against unit cost — it is not a question of which material is better.

Tungsten carbide — substantially harder and more wear-resistant than HSS, with die life under normal operating conditions running around two million pieces (actual figures vary considerably with screw material, machine condition and operating discipline). Suited to high-volume, stable, long-running specifications.

SKH high-speed steel (M2 / M9 / M51) — tougher and less prone to chipping, at a noticeably lower cost per die, but shorter life than carbide. Suited to smaller runs, trial production, or non-standard sizes that change often.

General guidance by screw material:

Screw material	Suggested die material	Notes
Carbon steel (SAE 1018–1022)	HSS or carbide	Trade off against volume and budget
Stainless 304	Carbide recommended	HSS life in stainless is typically much shorter
Stainless 316	Carbide recommended	Stronger work-hardening, harder on the die
Bi-metal (SS body + CS point)	HSS or carbide	Trade off against volume

Step 5: Decide whether you need a coating

PVD coating is not a default extra — it addresses specific failure modes.

Screw material	Common coating	What it addresses
Carbon steel / bi-metal	TiN or TiAlN (optional)	Extends life; pays off at higher volumes
Stainless 304	CrN	Suppresses galling (adhesive wear)
Stainless 316	AlCrN	Handles stronger work-hardening and heat load

On carbon steel, coating is an economic decision; on stainless, it is closer to a requirement. Stainless tends to adhere to the die surface during cold forging, and galling is among the common failure modes in these applications. Coatings like CrN work by reducing that adhesion tendency rather than simply adding hardness.

The sixth factor people skip: wire

The five steps above specify the die. How that die performs once it is in the machine depends on another variable: the wire.

Wire diameter determines the volume of material available during forming, which governs whether the point fills the cavity. Wire mechanical properties — tensile strength, reduction of area — govern whether it cracks during cold forging. The same die running different wire lots can produce visibly different point quality.

If your symptom is "nothing changed on the die but the screws went bad," the wire lot is often worth checking before the tooling. See our fastener wire mechanical properties reference for selection data.

Standard or non-standard?

Standard — conventional specifications falling within the L1–L7 series and IFI #4–#14 / DIN ST2.9–ST6.3. These generally have established process parameters and shorter lead times (standard samples typically run 3–4 working days).

Non-standard — the following are normally handled as custom work: special point geometries (large/small lightning point, YS lightning point, winged types), drill diameters outside the usual range, customer-proprietary geometry, or reproducing the dimensions of an existing die.

Reproducing an existing die is a very common request. If you have a die currently in production — even a worn one — sending the physical part or clear photos is usually more accurate than describing parameters.

Reverse diagnosis: what a wrong choice looks like

If the die is already on the line, you can work backwards from the symptom:

Symptom	Likely cause
Will not drill through, screw stalls	L-series undersized, flute length insufficient
Off-center point, hole drifts	Concentricity between die halves out of tolerance
Point chips early	Die material mismatched to screw material, or wire too hard
Material adhering to die surface, scoring	Stainless production without a suitable coating
Dimensions drifting gradually	Normal wear; replace on a life cycle
Will not fit the machine	Die style does not match the header's die pocket

These are common correspondences, not the only explanations — one symptom can have several causes, and actual troubleshooting should be backed by measured samples.

What to send with an RFQ

Any of these is enough to start, listed from most to least complete:

Ideal — screw drawing with point dimensions + screw material + target substrate thickness + header model

Most common — screw sample or the old die (physical part or photos) + approximate volume

Minimum — screw size (IFI number or DIN ST value) + drill diameter + substrate thickness + screw material

Missing drawings will not stop a quote. In practice most inquiries start from a sample photo or a short trial-run video: we make an initial assessment first, then decide whether a sample die is worth cutting.

Summary

The order is: standard and size → substrate thickness sets the L-series → screw size sets the style → screw material sets the die material → coating as needed. Thickness narrows the field, screw size converges it, material and coating come last.

Zhonglianda Precision Mold produces the full L1–L7 range in both tungsten carbide and SKH high-speed steel, covering IFI #4–#14 and DIN ST2.9–ST6.3. Standard samples typically take 3–4 working days, and we accept trial orders of a single die.

If you are unsure which series applies, use the drill point die selector to get candidate codes from your specifications, or send us sample photos for an initial assessment.