Non-standard geometry is the most common reason a carbon graphite part ends up as an RFQ: the shaft is too large to insert a one-piece ring, a thin wall with a high length-to-diameter ratio is required, spiral grooves have to be cut into the face to generate a liquid film, or the original part number has long been discontinued. That is exactly what we build here — we review the drawing and the duty first, then set the grade, the impregnation and the process route, and only after a first article passes inspection do we run the batch. Machining and impregnation happen in the same plant, so nothing is handed between two suppliers.
CNC turning produces OD, bore and steps, including high length-to-diameter thin-wall bushings; because carbon graphite is brittle, fixturing and tool paths are planned per part to avoid chipping.
Internal and external cylindrical grinding brings fit faces to the drawing's dimensional and surface requirements where the part locates against a housing or a shaft.
Seal faces are lapped individually and each one is flatness-inspected before packing, so transit chipping and scratching do not reach the customer.
Straight, spiral, wedge and particle-flush grooves can be cut on faces and bores to generate a liquid film, expel solids, or improve lubrication at start-up.
Drive holes, pin holes, tapped holes and relief holes are machined to drawing, with hole positions completed in a single setup relative to the face to hold position tolerance.
Machining before impregnation guarantees the pores fill and the final properties are uniform; machining after impregnation saves a finishing pass but increases tool wear and requires cutting parameters tuned to the impregnant. We do both and recommend one at quotation stage.
Two-, four- and six-segment rings have their joints lapped as a matched set and are delivered ring-by-ring as a set, for installation in enclosed cavities without pulling the shaft.
We can supply cut-to-size or near-net-shape blanks only — rod, tube, ring and block — for the customer to finish, reducing material loss and machine hours.
| Feature | Boundary |
|---|---|
| Bore & OD size | CNC to drawing; micron-level achievable, final call set by geometry |
| Seal face flatness | Individually lapped and inspected before packing |
| Seal face roughness | Lapped finish; specify Ra target on the drawing |
| Recommended shaft counterface | 304/316 stainless polished to about Ra 0.2 µm |
| Dry-running clearance | Typically 2.5 – 3‰ of shaft diameter, single side |
| Thin-wall & slender parts | First-article deformation check recommended before batch |
| Position & concentricity | Held by machining in a single setup; state the datum on the drawing |
| Grade | Max Temp | Notes for custom parts |
|---|---|---|
| M106 | 350°C | Standard carbon graphite, the general-purpose choice; easiest to machine unimpregnated |
| M106K | 220°C | Resin-impregnated, food and pharma oil-free duty |
| M106D | 500°C | Antimony-impregnated, high-temp anti-oxidation; hard on tooling |
| M191T | 600°C | Carbonized, for the highest chemical inertness requirement |
| Cu-impregnated | 400°C | Copper-impregnated for high-load, low-speed bearing parts |
PDF or DWG. Give bore, OD, height, which faces are seal faces, tolerance and surface requirements, and mark the working face.
STEP or IGES. Best for irregular geometry, curved surfaces or complex assembly relationships — we build tool paths directly from it.
No drawing is fine. We measure and reverse-draft the part, send you the drawing to approve, and only then schedule production.
Shaft diameter, speed, temperature, pressure, media and lubrication condition. With those six we can select the grade and clearance for you instead of only machining to shape.
Engineers check the dimension chain, wall thickness, seal-face location and duty, and flag anything in the drawing that would cause a machining or early-life failure.
The grade and impregnant are chosen from temperature, media and load, together with whether to machine before or after impregnation.
We issue the operation list, fixturing plan and inspection points, with price built from quantity and complexity.
A first article is produced, fully measured against the drawing and reported to you; batch scheduling follows your approval.
Machining, impregnation and post-processing move within one site, cutting the transit handling that chips brittle graphite.
Dimensions and seal faces are sampled or fully inspected against the drawing, then packed in individual cushioning and shipped with the inspection record.
Enclosed cavity with no shaft-end access — a one-piece ring cannot be fitted, so a 3- or 4-segment ring is machined instead
Original part number discontinued and only a worn sample exists — reverse-drafted and reproduced
Long thin-wall bushings with a high length-to-diameter ratio where a metallic sleeve cannot meet the corrosion requirement
Faces needing spiral or wedge grooves to generate a liquid film or flush catalyst particles
Large-diameter or irregular blocks cut near net shape to save material and machine hours
Combined support and sealing parts for reactor agitators, where machining and impregnation must stay in one plant
Yes. A first article is a normal step here: we make one to drawing, measure it fully against the drawing and send you the report before you decide on the batch. Batch price is computed from quantity and complexity, and we quote prototype and batch together.
Send the sample. We measure it, produce a 2D drawing (and a 3D model where the shape needs it) with dimensions, tolerances and seal-face locations marked, and return it for your approval. Production is scheduled only after you confirm, rather than machining against a guess.
Dimensions are held by CNC and grinding; micron-level is achievable, and the final value depends on geometry — thin-wall, slender and large-diameter parts get a first-article deformation check. Seal faces are lapped individually and flatness-inspected before packing. State the tolerance and surface requirement on the drawing and mark which face is the sealing face; we will flag anything we cannot hold and propose an alternative rather than accept the order and fail later.
Every shipment is inspected against the drawing for dimensions and seal faces and goes out with an inspection record. If you also need material certification, density and porosity data, or impregnation process records, tell us at order time and we issue them in the form your QA requires.
Yes. Drawings are used only for your quotation and production — not shared, not used to supply other customers, and never shown on our site. If you want it in writing, we will sign an NDA before you send anything.
Lead time follows geometric complexity, whether impregnation is needed, and how many impregnation and re-finishing cycles the part requires — impregnated parts must return to the grinding station afterwards, which is the step most often missed in non-standard quotes. We give expected durations for the prototype and each batch at quotation stage, and can arrange staged delivery for urgent needs.
