Carbide Hand Files for Die and Mold Work
Fitting, blending and finishing hardened tool steel with a file that keeps cutting
Why steel files quit where die work begins
Most hand work in a die or mold shop happens after heat treat, on punches, die sections, cavity blocks and core pins at Rc 58-62. A conventional steel file is hardened to roughly Rc 62-65, so its teeth are barely harder than the part. Above about Rc 40 they glaze and burnish instead of cutting, and the file is done in a few strokes.
Severance Tool developed and patented the carbide hand file as an improved version of the flat file. The teeth are ground into a solid tungsten carbide blank with a hardness rating of Rc 90+, so the file keeps cutting where a steel file will not. The carbide hand files product page lists the working figures: 100:1 life against steel files and 5 or more resharpenings.
Quick Answer
Carbide flat file for hardened tool steel, stainless, titanium and high nickel alloys.
Diamond file for carbide inserts, ceramics, glass and composites.
HSS file for interrupted cuts across slots or cross holes.
What makes a solid carbide file different
Severance grinds the teeth with diamond wheels rather than stamping or chiseling them, so the geometry is uniform across the face and the cut is predictable. The blog post on carbide hand file advantages covers the economics; the table below covers what matters at the bench.
| Property | Conventional steel file | Severance solid carbide file |
|---|---|---|
| Tooth material | High-carbon or alloy steel, about Rc 62-65 | Solid tungsten carbide, hardness rating Rc 90+ |
| Hardened steel | Glazes over above about Rc 40 | Cuts hardened tool steel, stainless, chrome plate and case-hardened surfaces |
| Wear resistance | Teeth dull within hours on steel | 10-20 times the abrasion resistance; 100:1 file life |
| Resharpening | Not economical; discarded | Reground by Severance 5 or more times at a fraction of new cost |
The catalog records one customer filing long beads of titanium weld: the old method used 40 to 60 steel files a day, and one Severance FJ-7-W carbide file did the work of 15 of them.
When a die or mold maker reaches for a carbide file
- Fitting punches and die sections. Bringing a hardened punch or die section to a working fit after heat treat. The catalog says its carbide machine files, which use the same ground teeth, cut hardened steel and often eliminate annealing and rehardening of critical tools.
- Blending parting lines. Taking down the mismatch where two cavity halves meet, with a fine standard tooth and light pressure.
- Removing EDM recast. The glassy recast layer from wire or sinker EDM skates a steel file; a fine-cut carbide file takes it to bright parent metal before stoning.
- Polish prep. Removing machining and grinding marks from a cavity wall ahead of stones and diamond compound, with the super fine and extra fine FE cuts.
Heavy stock removal is rotary work: Carbo-Mills and carbide burrs handle cavity finishing, parting line removal and electrode preparation under power; the hand file takes over for fitting and the final surface.
Carbide Die Files
Miniature files with a 2″ cutting surface on a 1/4″ cross-section, handles supplied: triangular, circular, rectangular, half-round, square and tapered triangle. EDP 20270 through 20295.
See all styles and EDP numbersFile styles and handle codes: FJ, FZ, FS and FE
Files are ordered by style prefix, cut number and material suffix. A -W suffix means solid carbide; without it, the same name is the high speed steel version, so FJ-5-W is the 6″ in-line carbide file in medium cut. Curved tooth files take an FC prefix (FCT, FCZ, FCS, FCE); -CB, -RASP and -DBL mark chip breaker, rasp and double cut.
| Style | Cutting area | Overall length | Cuts (teeth per inch) | Carbide standard cut EDP |
|---|---|---|---|---|
| FJ, 6″ stroke, in-line style | 3/4″ x 6″ | 11-3/4″ | Fine 40, Med. Fine 31, Medium 25, Med. Coarse 20, Coarse 16 | FJ-3-W to FJ-7-W, EDP 19770-19774 |
| FZ, 3″ stroke, offset handle (FZ-K adds a knob, 9-1/2″ OAL) | 3/4″ x 3″ | 8-3/4″ | Same five cuts as FJ | FZ-3-W to FZ-7-W, EDP 19795-19799 |
| FS, 3″ stroke, plain style | 3/4″ x 3″ | 6″ | Same five cuts as FJ | FS-3-W to FS-7-W, EDP 19845-19849 |
| FE, miniature file for fine detail | 3/8″ x 1-1/2″ | 6″ | Super Fine 62, Extra Fine 50, Fine 40, Med. Fine 31, Medium 25 | FE-1-W to FE-5-W, EDP 19870-19874 |
All four styles also come in curved tooth, chip breaker, rasp and double cut patterns, and in diamond (DCF) and CBN versions. Full EDP lists are on the styles and EDP numbers page and in the printable hand files catalog (PDF).
Tooth patterns and cuts
Cut (tooth density)
The cut number sets teeth per inch. Fine (40 tpi) is the finishing cut for hardened steel, medium (25) the general-purpose cut, and coarse (16) is for fast stock removal on softer material. Standard pattern in coarse, medium and fine cuts is stocked; other cuts and patterns are made to order.
Pattern
- Standard tooth: deburring and smoothing hardened and high speed steels such as M-2 and M-42 with light pressure. Supplied unless another pattern is specified.
- Curved tooth: fast removal with less loading on flat, curved and round surfaces.
- Chip breaker: same finish as standard tooth, and it cuts a little better because no long shavings are produced.
- Double cut: medium pressure for medium finishes and shaping.
- Rasp: heavy pressure and fast removal on soft material; roughest finish.
- Diamond grid and CBN grid: coarse or fine grit for carbide, ceramics, and high speed and high nickel alloys.
Technique on hardened steel
The carbide tooth is hard but brittle, so every habit that protects the edge also protects the file.
- Pressure on the forward stroke only. Lift slightly on the return; dragging back over hardened steel rubs the tooth crests without cutting.
- Full-length strokes, no rocking. Use the whole cutting area and keep the file flat; rocking rounds the edge you want square and loads one corner.
- Ease onto the work. Do not start a stroke on an edge. On slots and cross holes, switch to the HSS version; the catalog recommends steel files where chipping might occur on an interrupted cut.
- Clear chips often. Card in the direction of the teeth; steel chips are magnetic and pack between teeth. On aluminum, chalk the face first.
- Never pry, never drop. A drop onto a concrete floor is the most common cause of premature failure. Store it in a rack or slotted drawer so carbide never touches carbide.
Materials: carbide, diamond, CBN or HSS
Severance offers four file materials, covered in the trade press on the news page. Carbide covers hardened tool steel, stainless including 17-4 PH, titanium, Inconel and Hastelloy, chrome plate and hard coatings, and, with a curved tooth or rasp pattern, aluminum, bronze and cast iron. Diamond (FJ-DCF-F, EDP 19970, or FJ-DCF-C, EDP 19974) is for carbide inserts, hardened dies, ceramics, glass and composites; it needs very little pressure and does not load. CBN suits high speed rotary use on high speed and high nickel alloys with low heat. HSS, a molybdenum steel file with the same ground cutting action, is for interrupted cuts where carbide might chip. The tool selection guide and HSS vs carbide comparison cover rotary tools.
Selection table by die shop task
| Task | Style | Cut | Pattern | Notes |
|---|---|---|---|---|
| Fitting a hardened punch or die section | FJ flat | Medium (25), finish Fine (40) | Standard | Full strokes, check the fit often. |
| Blending a parting line | FJ or FZ offset | Fine (40) or Med. Fine (31) | Standard | Offset keeps hands clear of the other half. |
| Radiusing an insert or core pin edge | FE or half-round die file | Fine (40) | Standard | Roll through the radius, no rocking. |
| EDM recast or polish prep in a pocket | FE or FS | Fine (40) to Super Fine (62) | Standard | Short strokes, card often. |
| Deburring after finish grinding | FS or FZ | Medium (25) | Chip breaker | Finish retained, no long shavings. |
| Dressing a carbide insert or ceramic core | FJ diamond (DCF) | Fine or coarse grit | Diamond grid | Carbide will not cut carbide. |
Care and resharpening
Card the file after use, keep it in its own slot, and keep it off the floor. When it dulls, Severance regrinds its own carbide hand files in Saginaw, Michigan, at a fraction of new file cost; the product page lists 5 or more resharpenings, and standard regrind service turnaround is 1-3 weeks with rush available. Stocking distributors are on the where to buy page; resharpening questions are answered in the FAQ.
Frequently asked questions
Yes. Severance solid carbide hand files are ground from tungsten carbide rated Rc 90+ and cut punches, die sections and mold components hardened to Rc 58-62. A conventional steel file, at about Rc 62-65, glazes over above roughly Rc 40.
The FJ style, a 6″ stroke in-line file with a 3/4″ x 6″ cutting area, is the bench file for fitting and parting lines. Add an FZ offset handle for filing flush to a shoulder or inside a cavity, and an FE miniature (3/8″ x 1-1/2″, up to 62 teeth per inch) for radii and polish prep.
Keep the file flat, ease onto the work instead of striking an edge, put pressure on the forward stroke only, never pry with it, and store it in its own slot. For interrupted cuts across slots or cross holes, use the HSS version of the same file.
Severance lists 5 or more resharpenings. Dull files go to the Severance regrind service in Saginaw, Michigan, with a standard turnaround of 1-3 weeks at a fraction of the cost of a new file.
Yes. The catalog lists special shapes, sizes and cuts on short notice, custom carbide machine files made to specified sizes, shapes, cuts and mounting dimensions, and special hand and die files in carbide, high speed steel, diamond or CBN. Send details through the contact page for a quote.