Materials and tolerances
PEEK CNC, metals, and tolerances for medical and IVD parts
What Shenzhen Kangsenlong Technology machines, the tolerance bands we already publish, and the drawing notes that let a buyer get a straight quote for medical CNC and IVD components.
Kangsenlong is a machining shop in Bao'an, Shenzhen. The work is drawing-based components for medical equipment, in-vitro diagnostic instruments, and analytical systems: PEEK and other engineering plastics, plus corrosion-resistant metals. This page is the material and tolerance reference behind the PEEK CNC, IVD machining, and medical CNC pages.
A family name is not a specification. "PEEK", "stainless", or "medical grade" does not tell us which lot to buy or which tolerance is realistic. The tables below use the grades and the bands already stated on this site. They are a starting point for the drawing review, not a blanket capability stamped on every feature.
Metals
Metals for medical CNC and instrument parts
Critical features on stable metal parts are often discussed from ±0.005 mm to ±0.01 mm. Machine positioning published for the shop is ±0.005 mm on 5-axis milling, ±0.008 mm on 3-axis and 4-axis milling, and ±0.005 mm concentricity on turning.
| Material | Grades we machine when the drawing names them | Tolerance context | What to put on the drawing |
|---|---|---|---|
| Aluminum | 6061-T6, 7075-T6, MIC-6 cast plate | ±0.01 mm is a common critical-feature callout. Selected datum features are reviewed toward ±0.005 mm. | Temper, which faces are datums, which faces are cosmetic, and any anodize or other treatment as its own line. |
| Stainless steel | 316L, 17-4PH | Same metal band on stable milled or turned features. | 17-4 condition if strength is controlled. Passivation only if you need it included in the route. |
| Titanium | Ti-6Al-4V / Grade 5 | Same metal band, reviewed more carefully on thin walls. | Alloy specification. These are equipment components. This page is not an implantable-device claim. |
| Copper and brass | Oxygen-free copper, brass | Same metal band on stable features. Soft grades bruise if the clamp and the burr callout are vague. | Temper, and whether the surface is an electrical contact or only a cosmetic face. |
| Tool steel and high-temperature alloys | The grade written on your drawing | Quoted from that specification. These alloys are not assumed to machine like 316L. | Full specification, hardness condition, and any heat treatment you expect after machining. |
Treatments such as anodize, passivation, plating, and heat treatment are not part of the default machining route. List them on the RFQ if the part needs them.
Engineering plastics
PEEK CNC and other instrument plastics
The figures match the tolerance matrix on the PEEK machining page. Fluoropolymers are wider than PEEK on purpose. Stress-relieved PEEK and similar plastics are often discussed from ±0.01 mm to ±0.025 mm on critical features.
| Material family | Grades buyers specify | Standard CNC tolerance | High-precision review | Typical instrument use |
|---|---|---|---|---|
| PEEK | Natural 450G, GF30 (30% glass), CA30 (30% carbon), bearing grade. Medical-grade or USP Class VI resin only when that grade is specified and the lot certificate supports it. | ±0.025 mm | ±0.010 mm | HPLC-style fittings, valve rotors and stators, insulators, IVD mounts |
| PTFE / PVDF / PCTFE | Virgin PTFE, glass-filled PTFE, PVDF, PCTFE | ±0.050 mm | ±0.020 mm | Reagent valve bodies, seats, chemical seals |
| PEI (Ultem) and PPS | Ultem 1000, Ultem 2300, PPS | ±0.025 mm | ±0.012 mm | Sterilization hardware, manifolds, electrical insulators |
| PMMA / PC / POM | Cast optical acrylic, polycarbonate, acetal copolymer | ±0.030 mm | ±0.015 mm | Visual fluid blocks, reservoirs, low-friction bushings |
PP is also in the machining scope when the drawing names it. A trade name such as Delrin, Kynar, or Ultem is used only when you specify that product, not as a substitute for the whole polymer family.
For PEEK CNC parts with thin walls, deep pockets, or an asymmetric shape, the route is rough machining, an intermediate anneal when the geometry needs it, then finish machining. Plastic jobs use dedicated sharp tooling and a clean air blast or a water-based coolant so oil and metal fines stay out of a fluid path. That process is described in more detail on the PEEK machining page.
How to read a tolerance on an IVD or analytical part
For IVD machining in Shenzhen, the number on your drawing is the acceptance standard. The tables are how we start the conversation.
Machine positioning and part tolerance are different things. A 5-axis positioning figure of ±0.005 mm does not mean every hole in a large plastic housing will be quoted at ±0.005 mm. Plastics move when stress relaxes, and they move with temperature and moisture. PEEK is more stable than PTFE. That is why the plastic table is wider than the metal line, and why PTFE is wider than PEEK.
Put the tight tolerance on the feature that controls the function: a sealing diameter, a port position, a bearing bore, a datum face. A profile tolerance wrapped around an entire plastic housing adds setups and inspection time without improving the seal. Datums should match how the part is assembled, not how it happened to be modeled.
Agree the inspection method for any feature tighter than the standard band. A thread is accepted with the gauge called out on the drawing. A sealing land is accepted against the surface texture you specify, often as an Ra value on that face only. We do not apply a default Ra to the whole part.
The same rules sit behind the part examples. A PEEK connector, a multiport IVD block, and a PTFE seat do not share one tolerance.
Drawing callouts
What buyers should put on the drawing
These are the notes that keep a medical CNC or PEEK CNC quote from coming back as a question list. They also belong in the RFQ checklist.
- 01
Material grade, not only the family
Write the grade, the condition or filler, and any required certificate (lot traceability, RoHS, REACH, or a resin compliance statement such as FDA 21 CFR 177.2415 or USP Class VI). A compliance statement on a resin is a material fact. It is not a device clearance.
- 02
Revision, units, and datums
One current revision. Units that match the model. Primary datums labeled the way the part is located in the instrument.
- 03
Critical features marked
Flag the dimensions your incoming inspection will measure. Leave reference dimensions as reference. If everything is critical, nothing is.
- 04
Threads and sealing faces
Thread designation and class, and whether a go/no-go gauge is required. Surface texture on the sealing or bearing face only. Edge break or a burr allowance on internal cross-holes.
- 05
Cleanliness, cosmetics, and quantity
A cleanliness note if the part is a fluid path. Cosmetic zones only where appearance matters. Prototype quantity and the repeat quantity you expect, plus the inspection package: material certificate, first-article, CMM, or visual.
We will not assume anodize, passivation, heat treatment, leak testing, or a regulatory filing. If one of those is required, write the specification and who owns the acceptance criteria.
Drawing-based quotation
Send the grade and the critical feature.
We review feasibility against your drawing before we quote a tolerance. A table on this page is not an acceptance of every callout.