How to Read a FAE Teeth Specification Sheet Before Making a Sourcing Decision
Specification sheets for FAE mulching teeth look straightforward — a list of dimensions and material claims. But the values that actually determine whether a set of teeth is the right choice for your application aren’t always the ones that get highlighted, and the claims that sound most important (premium carbide, high hardness, maximum durability) are often the least specific. Reading a spec sheet well means knowing which values matter, what they tell you, and what to look for when they’re missing.
Shank dimensions: the compatibility check
The shank is the part of the tooth that seats into the holder on the FAE rotor. FAE uses a specific retention geometry — a keyed shank that locks into the holder pocket and is retained by a pin or bolt depending on the head model. Aftermarket teeth must replicate this geometry precisely to install correctly and retain safely at operating speed.
The dimensions that matter for shank compatibility are: shank diameter, shank length, and the geometry of the key or groove that engages the holder. On a spec sheet, these should appear as nominal values with tolerance ranges — not just nominal values alone. Tolerances tell you how much variation is permissible between individual teeth from the same batch.
If a spec sheet only shows nominal shank dimensions without tolerances, that’s a gap worth filling. Ask the supplier directly: “What is your production tolerance on shank diameter?” The answer tells you how tightly they’re controlling the dimension that determines whether the tooth fits and stays in the holder.
Carbide grade: what’s actually specified
The carbide tip specification is where the most meaningful differentiation between tooth suppliers exists, and it’s where spec sheets are most frequently vague. Claims like “tungsten carbide tips,” “premium grade carbide,” or “high hardness carbide” don’t give you the information needed to compare products or predict performance.
What a useful carbide specification includes:
Carbide grade designation (ISO K-grade or equivalent): K01–K10 indicates harder, more wear-resistant grades for cast iron and abrasive materials; K20–K40 indicates tougher grades for interrupted cutting and impact. For rocky, mineral-rich forestry work, a K10–K20 grade is typically appropriate — hard enough for wear resistance, tough enough for impact from rock contact.
Cobalt content percentage: cobalt is the binder in tungsten carbide. Higher cobalt content increases toughness and impact resistance; lower cobalt content increases hardness and wear resistance. A specification that states cobalt content (typically 6–15% for forestry applications) is more informative than one that only states a hardness value.
Hardness value (Vickers or Rockwell A): useful as a reference point, but hardness alone doesn’t fully describe carbide performance. Two carbide grades can have similar hardness but different toughness depending on grain size and cobalt content.
Steel body specification
The steel shank body needs adequate toughness to absorb impact without fracturing, since the carbide tip handles wear resistance but not shock absorption. A body that’s too hard is brittle; one that’s too soft deforms and affects the seating geometry for the carbide insert.
Typical steel body specifications for forestry mulching teeth use medium-carbon alloy steel at 35–45 HRC after heat treatment. If the spec sheet only describes the steel as “alloy steel” or “heat-treated steel” without a hardness range, that’s a vague specification — functional but not precise enough for comparative evaluation.
Brazing specification
The connection between the carbide tip and the steel shank is the critical joint in the tooth assembly. A brazing specification should state the alloy used (silver-copper brazing alloys are common for carbide-to-steel joints), the nominal brazing thickness, and whether inspection is performed to detect voids.
Most spec sheets don’t include brazing specifications, which makes this a question worth asking directly rather than expecting to find on a product data sheet. The question itself — “what brazing alloy do you use and how do you inspect bond quality?” — is a useful test of the supplier’s technical depth.
Weight and balance data
For aftermarket teeth replacing a full set on an FAE rotor, weight consistency across the batch matters for rotor balance. A spec sheet that includes nominal tooth weight and a permissible weight variance (e.g., ±5g or ±10g) is giving you information that directly affects rotor balance quality after installation.
See https://www.jyfmachinery.com/product/fae/ for product specifications covering multiple FAE mulching head models, including dimensional data and application guidance for carbide tooth selection by machine type. Having the supplier’s specification in front of you before a technical conversation makes it easier to identify which values are clearly defined and which ones need follow-up.
What to do when the spec sheet is incomplete
Most aftermarket FAE teeth spec sheets will be missing at least some of the above. The response isn’t to reject any supplier whose spec sheet isn’t complete — it’s to use the gaps as questions. A supplier who can answer the carbide grade, tolerance, and brazing questions clearly when asked is demonstrating that the information exists even if it wasn’t published. A supplier who can’t answer them, or answers them vaguely, is telling you that the production process isn’t controlled to that level of specificity.
