| HS Code | 540569 |
| Density | 1.01 g/cm³ |
| Tensile Strength | 50 MPa |
| Elongation At Break | 50% |
| Tensile Modulus | 1800 MPa |
| Charpy Impact Strength | No break |
| Ball Indentation Hardness | 70 N/mm² |
| Shore D Hardness | 76 |
| Melting Point | 178 °C |
| Thermal Conductivity | 0.23 W/(m·K) |
| Coefficient Of Linear Thermal Expansion | 12 × 10⁻⁵ /K |
| Maximum Continuous Service Temperature | 80 °C |
| Maximum Short Term Service Temperature | 120 °C |
| Water Absorption At Saturation In Air | 0.5% |
| Water Absorption At Saturation In Water | 1.5% |
As an accredited Murtfeldt Murdopol Nylon 12 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Murtfeldt Murdopol Nylon 12 is supplied in 25 kg sealed polyethylene bags, palletized and stretch-wrapped to protect from moisture and handling damage. |
| Container Loading (20′ FCL) | 20′ FCL container loading of Murtfeldt Murdopol Nylon 12 ensures secure, efficient transport with optimized weight distribution and stable cargo restraint. |
| Shipping | Murtfeldt Murdopol Nylon 12 ships as a solid engineering plastic, non-hazardous under normal conditions. Pack in sealed moisture-resistant bags or crates to prevent contamination. Avoid extreme heat and prolonged UV exposure. Use standard dry freight with secure loading; no special hazmat or temperature-controlled transport required. |
| Storage | Store Murtfeldt Murdopol Nylon 12 in a cool, dry, well-ventilated area, away from direct sunlight, UV radiation, and excessive heat. Keep in original, sealed packaging to prevent moisture absorption and contamination. Avoid contact with strong oxidizers. Maintain ambient temperatures and low humidity. Properly stored, the material retains its properties for several years. |
| Shelf Life | Shelf life is virtually unlimited if stored dry, cool, and dark, protected from UV radiation and moisture. |
In heavy-duty diesel platforms operating under Euro VI and EPA 2010 evaporative emission limits, machined PA12 connector bodies derived from Murdopol Nylon 12 rod stock are turned and milled into fuel vapour return and tank venting fittings where low permeation, resistance to zinc chloride from winter road de-icing, and minimal moisture drift are specified simultaneously. The stock is unfilled at 0 wt% glass fibre and 0 wt% plasticiser, with a heat-stabiliser package suitable for under-bonnet exposure; production lots are cross-cut from 40 mm and 60 mm diameter rod and machined on single-spindle CNC lathes with positive-rake polished carbide inserts at 150–250 m/min surface speed and 0.05–0.15 mm/rev feed. After first-operation turning, the parts are stress-relief annealed at 160 °C ±5 °C for 1 h per 25 mm of maximum wall thickness in a nitrogen-purged forced-convection oven; the anneal is not optional because residual machining stress in a 60 mm connector body will otherwise contribute to post-assembly creep during engine-compartment heat soak. The terminal components include quick-connector sleeves, diagnostic test-port bodies, and barbed service tees. The operational window spans −40 °C cold-soak to 60 °C at the tank sender flange; at 23 °C and 50 % RH under ISO 291 conditioning, PA12 takes up only 0.5–0.7 % moisture by weight, and full saturation under ISO 62 is approximately 1.5–1.8 %, which keeps push-fit retention force more stable than flexible PVC or PA6 alternatives in humid conditions. Fuel-contact reference grades of PA12 tubing are typically qualified to DIN 73378 and SAE J2260 for low-permeation wall sections, while the machined fitting itself is subjected to thermal shock and pressure-pulse cycles based on ISO 16750-4; published data for this specific machined fitting configuration is limited, so first-article validation on production-representative CNC fixtures is required. The parts are retained with stainless steel clips rather than solvent-based adhesives, and strong mineral acids, phenolic solvents, and halogenated cleaning agents are excluded from the service environment because they can attack the amide linkage in unstabilised PA12 grades.
Globe-type valve seats machined from PA12 sheet are installed in demineralised water return circuits where austenitic stainless seats suffer wire drawing at water velocities above 2.5 m/s and where elastomer lips fail by swelling in ozonated water. The dry-machined seat has a tensile modulus near 1400–1600 MPa under ISO 527-2, but water immersion changes the risk profile through simultaneous swelling and stress relaxation. The seat is not a direct substitute across the entire water-treatment envelope, because continuous demineralised water service above 70 °C produces progressive loss of seating contact pressure. Production from Murdopol Nylon 12 sheet uses rough sawing, CNC milling with 0.5 mm finish stock, stress-relief annealing at 160 °C for 1 h per 25 mm thickness, finish turning, and face lapping to a flatness of 0.005 mm per 25 mm diameter. The terminal components are globe-valve seat rings, back-up rings for diaphragm actuators, and spring-loaded check-valve poppets where the poppet body is PA12 and the spring is 316 stainless steel.
| Condition | Typical published PA12 response | Machined seat design response |
|---|---|---|
| 23 °C, 50 % RH, ISO 291 | Equilibrium moisture uptake 0.5–0.7 %; linear change 0.15–0.25 % | Baseline clearance condition for DN25 seats |
| 23 °C water saturation, ISO 62 | Water uptake 1.5–1.8 %; linear change 0.45–0.60 % | Increase radial clearance at the seat lip; pre-soak before final lapping |
| 60 °C demineralised water | Saturation kinetics accelerate; product-specific data limited | Soak inspection after 24 h; derate differential pressure |
| 80 °C demineralised water continuous | Outside continuous service envelope; stress relaxation accelerates | Avoid; select PVDF or PPSU seat |
Compliance for water service is governed by the installed system rather than a single polymer standard: NSF/ANSI 51 applies to food-zone components, NSF/ANSI 61 applies where potable-water contact is claimed, and pharmaceutical WFI circuits require extractables assessment at the actual surface-to-volume ratio. PA12 stock can carry a food-contact declaration under FDA 21 CFR 177.1500 for certain applications, but the finished component must be re-assessed because machining coolants and annealing residues affect the surface. Sealing faces are polished to Ra ≤0.4 µm and inspected for tool chatter; surface microcracks act as hydrolysis initiation sites when the circuit is sanitized with hot alkaline detergents above pH 9 at 60 °C. In continuous demineralised water above 70 °C, the PA12 seat is replaced by PVDF or PPSU, and the PA12 component is limited to ambient-temperature water service where its lower moisture growth relative to PA6 is the primary technical advantage.
In beverage filling lines where external chain oil is prohibited by audit requirements, CNC-routed PA12 sheet components are machined into interlocking neck-guide rails, star wheels, and transfer fingers for PET bottle lines running 10,000–60,000 bottles per hour. The stock is unfilled and natural in colour, with 0 wt% graphite, PTFE, silicone oil, or plasticiser; the finished guide surfaces therefore do not shed solid lubricants onto PET containers. Machining is performed on 10 mm, 15 mm, and 20 mm PA12 sheet using vacuum-chucked CNC routers at 18,000–24,000 rpm spindle speed and 2,000–4,000 mm/min feed to achieve an edge finish of Ra ≤0.8 µm; outer profiles are then flame-polished with an oxidising flame at a traverse speed of 150–250 mm/s. Dovetail interlocking joints are cut with a 60° included-angle cutter, and adjacent rail segments are either dry-fitted to permit thermal movement or hot-gas welded using a PA12 welding rod at 240–260 °C; the melting peak of PA12 under ISO 11357-3 is 175–180 °C, so the welding gas temperature must not fall below 230 °C or the root fillet loses interdiffusion strength. Terminal parts—PET neck guide rails, bottle separator blocks, and infeed scroll wraps—operate at 4–40 °C under wet/dry cycling; the low equilibrium moisture uptake of PA12 at 23 °C and 50 % RH under ISO 62 is 0.5–0.7 %, which reduces seasonal linear variance compared with PA6. Food-contact status is validated under EU 10/2011 with overall migration below 10 mg/dm² for aqueous and 3 % acetic acid simulants at 40 °C for 10 days, and the base nylon resin is referenced under FDA 21 CFR 177.1500; black-carbon-filled grades must be segregated unless the carbon black meets the relevant direct-contact purity specification. Hot-gas welding requires the sheet surface to be dried below 0.15 % residual moisture; higher moisture creates steam porosity in the weld zone and reduces joint strength below 50 % of parent-sheet values. Pre-drying is therefore conducted at 80 °C for 4–12 h in a desiccant dryer, with moisture checked by a calibrated capacitance meter before welding.
Pneumatic restrictor fittings and silencer bodies for rolling-stock brake-control panels are machined from PA12 hollow bar and solid rod where the parts must tolerate compressor oil mist, temperatures down to −50 °C, and repeated pressure pulses from 0 to 1.0 MPa. The turret-lathe process uses single-point thread chasing rather than tapping to avoid notch-sensitive cut-thread roots; thread roots are radiused to 0.2 mm minimum, and the parts are annealed at 160 °C for 1 h per 25 mm after machining to reduce microcracking before assembly. The unfilled PA12 body is joined to EPDM seals and 316 stainless insert rings; zinc-plated steel is excluded from direct contact because zinc chloride formed in moist brake-panel atmospheres is a known stress-cracking agent for polyamides, even though PA12 is more resistant than PA6 or PA66. The terminal products include threaded silencer bodies with M10×1.0 and M12×1.0 ports, orifice restrictors with 0.5 mm orifices, and banjo fittings for 6 mm nylon tube. Fire-smoke-toxicity compliance under EN 45545-2 must be verified for the specific wall section and end-use location; unfilled PA12 typically does not reach HL3 without a halogen-free flame-retardant or intumescent package, so exposed brake-panel fittings are often enclosed in a steel cabinet or re-specified in a flame-retardant PA12 compound if the rail operator requires HL3.
When overhead conveyor systems require cable-carrying rollers with tight running clearances, unfilled PA12 rod is machined into twin-groove rope rollers and chain guide blocks because seasonal moisture uptake remains below that of cast PA6. At 23 °C and 50 % RH under ISO 62, PA12 absorbs approximately 0.5–0.7 % moisture while PA6 absorbs 2.5–2.8 %; full water saturation for PA12 is 1.5–1.8 %, compared with 9–10 % for PA6. The gap is critical in roller designs machined with a 0.02 mm running clearance on a stainless shaft: a PA6 roller can tighten onto the shaft after seasonal humidity exposure, whereas the PA12 roller remains free. Machining is performed from 60 mm and 80 mm diameter rod on a twin-spindle lathe with the outside diameter, groove profile, and bearing pocket cut in a single clamping to keep radial runout below 0.03 mm; rollers are then stress-relief annealed at 160 °C for 1 h per 25 mm and dynamically balanced to ISO 1940-1 Grade G6.3 at 1500 rpm. The groove geometry for 8 mm steel cable uses a root radius of 4.5 mm and a 30° flare angle. Terminal parts include cable sheave liners, twin-groove rope rollers, and chain guide blocks. The component is not intended for permanent shaft temperatures above 80 °C because creep at the bearing pocket can reduce interference fit; with a coefficient of linear thermal expansion near 1.1–1.3 × 10⁻⁴ K⁻¹, a 250 mm diameter roller expands by approximately 1.1–1.2 mm in diameter across a 20 °C to 60 °C shift, so the shaft shoulder requires axial clearance not less than 1.5 mm. Material density under ISO 1183-1 is 1.01–1.02 g/cm³, which reduces unsupported roller mass compared with brass or steel alternatives without requiring fibre reinforcement.
Machined from Murdopol Nylon 12 rod stock, single-lumen and multi-lumen catheter hub bodies, strain-relief collars, and torque-handle interface rings are produced for interventional devices where the hub must bond to a braided polymer shaft and withstand a 1 kg torsional load without cracking. The stock is unfilled and processed without plasticiser, colourant, or epoxy-based coating; sliding-headstock lathes with high-pressure coolant at 70 bar clear the small internal bores, and the parts are transferred to an ISO 14644-1 Class 8 cleanroom for ultrasonic washing in deionised water at 55 °C followed by drying at 60 °C until residual moisture is below 0.2 %. Terminal hubs are joined to Pebax or polyurethane catheter shafts by cyanoacrylate or UV-cure adhesive after plasma or corona surface treatment; unmodified PA12 bond strength is limited by low surface energy, and a plasma setpoint of 300–500 W with a 20–40 mm/s treatment speed is common in assembly. Biocompatibility acceptance is based on ISO 10993-5 cytotoxicity and ISO 10993-10 skin sensitisation and irritation testing of the finished device, not the raw stock alone; supplier documentation to USP <87> or USP <88> does not automatically cover machining coolants, cleaning agents, or labelling inks applied downstream. For this reason, dedicated production lots are segregated, and no rust-preventive oil is applied to bars used for medical components. Sterilisation preference is ethylene oxide because gamma radiation at 40 kGy can shift mechanical properties and colour in the unfilled stock depending on the heat-stabiliser package; after ethylene oxide processing, residual limits are managed under ISO 10993-7. The PA12 hub is not intended for long-term implant contact; if the device requires tissue contact beyond 30 days, the finished component must be reassessed under ISO 10993-6 implantation requirements and the specific stabiliser package of the Murdopol grade must be reviewed.
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Murtfeldt Murdopol Nylon 12 is a semi-finished polyamide 12 stock shape supplied as extruded plate, round bar, and hollow bar for machined components that require lower equilibrium moisture uptake than extruded or cast PA6 and PA66 grades. The polymer backbone is produced from laurolactam and contains a lower amide group density than PA6; this structural difference is the primary source of lower density, lower water absorption, and slower hygroscopic dimensional movement. Typical density measured to ISO 1183-1 is 1.01 g/cm³ to 1.02 g/cm³. The semi-finished stock is produced with controlled stress-relief history to reduce machining distortion, although grade-specific residual stress data are not publicly itemised for every Murdopol Nylon 12 format. Natural and black variants are available; black pigmentation with carbon black is used where UV exposure may occur, but it can alter surface resistivity and moisture uptake compared with the natural grade.
Typical service environments for Murdopol Nylon 12 include components exposed to aliphatic hydrocarbons, diesel, lubricating oils, greases, and zinc chloride solutions. In these media PA12 is less prone to environmental stress cracking than PA6 and PA66 because of the reduced amide concentration in the polymer chain. Continuous immersion in strong mineral acids, concentrated formic acid, phenols, or hot chlorinated solvents is not recommended. The maximum continuous service temperature for unfilled nylon 12 in mechanically unloaded conditions is commonly cited in the range 80 °C to 100 °C, with short-term peaks up to 120 °C; published values include safety factors that account for creep and oxidative ageing.
Polyamide 12 contains a lower density of amide groups than PA6 and PA66; equilibrium moisture content at 23 °C and 50 % RH according to ISO 62 is typically 0.5 % to 0.7 %, compared with 2.5 % to 3.0 % for unmodified PA6 and 2.0 % to 2.5 % for PA66. Saturation moisture uptake in water at 23 °C is approximately 1.4 % to 1.6 % for nylon 12, while PA6 can reach 9 % to 10 %. The resulting linear swelling from the dry-machined state to 50 % RH equilibrium is approximately 0.2 % for PA12 and near 0.6 % to 0.7 % for PA6. For a machined bearing with a diameter clearance of 0.10 mm, that differential can be the margin between free rotation and seizure. Post-machining conditioning at 23 °C/50 % RH for 24 h to 48 h is therefore performed before final metrology when the application has a critical clearance. Components that must function in dry winter air and humid washdown conditions should be sized using the saturated moisture dimension rather than the as-machined dimension.
| Property | Murdopol Nylon 12 | PA 6 | PA 66 |
|---|---|---|---|
| Density (ISO 1183-1) | 1.01–1.02 g/cm³ | 1.13–1.14 g/cm³ | 1.14–1.15 g/cm³ |
| Tensile modulus, dry (ISO 527-1/-2) | 1,400–1,600 MPa | 3,000–3,300 MPa | 3,100–3,500 MPa |
| Equilibrium moisture, 23 °C/50 % RH (ISO 62) | 0.5–0.7 % | 2.5–3.0 % | 2.0–2.5 % |
| Saturation moisture, 23 °C water (ISO 62) | 1.4–1.6 % | 9–10 % | 8–9 % |
| Notched Charpy, 23 °C (ISO 179-1/1eA) | 8–14 kJ/m² | 5–8 kJ/m² | 5–8 kJ/m² |
| CLTE, 23 °C to 60 °C (ISO 11359-2) | 90–130 × 10⁻⁶ K⁻¹ | 80–100 × 10⁻⁶ K⁻¹ | 80–100 × 10⁻⁶ K⁻¹ |
| Melting point (ISO 11357-3) | 172–178 °C | 220–225 °C | 255–260 °C |
The comparison table uses representative values for unmodified semi-finished nylon materials where exact Murdopol Nylon 12 grade-specific data are not publicly available. The use-related consequence is not strength superiority but dimensional predictability: a PA12 guide rail exposed to washdown humidity can hold a stable slot width with less compensation than PA6. The lower tensile modulus of nylon 12 must be accepted. Under identical cross-section, PA12 deflects more at a given load than PA66, so stiffness-limited structural parts may not be valid replacements despite the dimensional advantage.
Tensile yield stress measured to ISO 527-1/-2 on dry test specimens is typically 40 MPa to 45 MPa; after conditioning at 23 °C/50 % RH, the value is commonly 33 MPa to 38 MPa. Tensile elongation at yield is 4 % to 6 %, and elongation at break in dry specimens exceeds 200 %. Flexural modulus to ISO 178 is approximately 1,200 MPa to 1,500 MPa dry and 800 MPa to 1,000 MPa conditioned. Shore D hardness to ISO 868 is commonly reported near 70–75. Compressive yield strength to ISO 604 for dry unmodified nylon 12 is commonly cited at 45 MPa to 60 MPa, lower than the 70 MPa to 90 MPa typical of PA6 and PA66. This lower compressive strength means that high-contact-stress components require lower design safety factors if PA12 is substituted into an existing PA6 or PA66 assembly.
Machining Murdopol Nylon 12 on production turning centers is performed with high-positive-groove carbide inserts; published guidance for nylon 12 suggests rake angles of 10° to 15°, clearance angles of 5° to 8°, and surface speeds in the range 200 m/min to 400 m/min for roughing, reduced to below 150 m/min for finishing passes where local frictional heating can push surface temperatures into the Vicat softening range. Coolant is normally omitted on sawing and turning operations, but water-soluble emulsions of 5 % to 7 % concentration are used in deep-hole drilling to evacuate chips. The stock generates continuous chips; high feed rates are preferred over low feed rates to avoid melting and smearing at the tool edge. In production drilling of PA12 tubes, peck cycles of 0.5 × diameter are used to prevent chip packing and localised thermal expansion. Tooling with detectable flank wear above 0.2 mm can raise cutting force and produce dimensional drift through heat generation before complete failure.
Workholding requires attention to low compressive stiffness; chucking pressure on thin-walled PA12 bushes can introduce elastic deformation that is partially released after finishing. Stress-relief annealing at 160 °C to 165 °C in mineral oil or nitrogen is referenced in published processing guidance for polyamide 12; the soak time is commonly 1 h to 2 h per 25 mm of wall thickness. Annealing after rough machining can be preferable to annealing only before final finishing because it removes bulk residual stress before the last light pass. Parts that will operate near their service temperature should be seasoned through a thermal cycle before final inspection; otherwise the first field exposure to 70 °C can produce a step change of several hundredths of a millimetre in clearance-critical bores.
Nylon 12 retains ductility at sub-zero temperatures better than many unmodified polyamides. Notched Charpy impact at -30 °C according to ISO 179-1/1eA is frequently reported at 6 kJ/m² to 10 kJ/m² for unmodified PA12, while PA6 and PA66 can drop below 3 kJ/m² to 5 kJ/m² depending on moisture state. The combination of low-temperature impact ductility and resistance to aliphatic hydrocarbons makes the material candidate for sensor housings, fuel filler flaps, low-pressure fuel line clips, and quick-connect retainers. In these applications PA12 resists swelling and stress cracking in diesel and lubricating oils better than PA66; however, biodiesel blends containing aggressive trace acids and methanol can reduce resistance, so immersion testing in the actual production fuel specification is required. Published data for Murdopol Nylon 12 in specific biodiesel formulations is limited.
Chemical resistance follows the lower amide density. PA12 is not attacked by aliphatic hydrocarbons, mineral oils, greases, alkaline solutions, or salt solutions at ambient temperature. Aromatic hydrocarbons cause limited swelling. The material is unsuitable for continuous exposure to hot concentrated mineral acids, phenol, cresol, formic acid, acetic acid above 10 % concentration at elevated temperature, and chlorinated hydrocarbons used in vapour degreasing. Stress cracking tests conducted under constant strain with 1 % outer fibre strain and immersion in zinc chloride solution are used for comparative ranking; PA12 outperforms PA6 and PA66 in such evaluations. In fuel-contact components, the operating temperature is limited by the fuel itself and by long-term oxidative stability of the polyamide; continuous exposure above 80 °C in oxygen-rich dry air can reduce molecular weight and tensile elongation.
In unlubricated sliding against ground steel with surface roughness below Ra 0.4 µm, unfilled nylon 12 exhibits a dynamic coefficient of friction typically quoted between 0.30 and 0.45 at contact pressures below 0.5 MPa and sliding speeds below 0.1 m/s; above these conditions, frictional heating dominates and can exceed the short-term service temperature. The pressure-velocity limit for continuous dry operation of unmodified nylon 12 is often stated near 0.10 MPa·m/s to 0.15 MPa·m/s, but published data for the exact Murdopol Nylon 12 formulation is limited. In clean environments, wear is mild and abrasive; with hard particulates, the soft matrix loses material more rapidly. PA12 is not a substitute for internally lubricated PA6 grades in high-speed dry sliding applications.
Murdopol Nylon 12 natural grade can be assessed for food-contact use under EU 10/2011 and FDA 21 CFR 177.1500 for polyamide resins; specific migration results depend on the exact formulation and processing aids, so a supplier declaration is required before use. Black grades require separate evaluation because carbon black and processing stabilizers may alter overall migration. The material is not inherently flame-retarded; unfilled polyamide 12 typically meets UL 94 HB at stock thicknesses above 3 mm. Electrical surface resistivity under dry conditions is commonly in the range 10¹¹ Ω to 10¹³ Ω per IEC 62631-3-2, and volume resistivity near 10¹³ Ω·m to 10¹⁵ Ω·m per IEC 62631-3-1; moisture conditioning lowers these values by several orders of magnitude. For static-sensitive environments, carbon-black grades may provide limited static dissipation, but surface resistivity should be verified because it is not equivalent to a conductive or static-dissipative engineering plastic.
Extruded PA12 stock carries residual stress from cooling rate gradients across the cross-section; removal of asymmetric material during machining releases that stress and can produce measurable out-of-roundness. The standard corrective sequence is rough machining, stress-relief annealing, semi-finishing, conditioning, and final finishing. In production cells this sequence is implemented because the cost of an additional setup is lower than the cost of field returns from clearance drift. Published PA12 annealing guidance indicates a soak temperature of 160 °C to 170 °C under nitrogen or mineral oil for 1 h per 25 mm of section, followed by slow cooling at 10 °C/h to 20 °C/h to below 80 °C before removal. Annealing in air is possible but can cause surface oxidation; therefore inert-gas or oil bath is specified for parts that require close tolerance surfaces.
Post-annealing conditioning at 23 °C and 50 % RH for 48 h to 120 h is used to stabilise moisture-dependent dimensions. For components manufactured in winter, where indoor RH can drop below 20 %, the as-machined dry dimensions may be up to 0.2 % smaller than after summer conditioning. Machined seals and sliding elements installed in compressed air systems should be tolerance-stacked using the conditioned dimension rather than the immediate post-machining dimension. In high-speed rotating assemblies, the lower density of nylon 12 reduces centrifugal stress at the same rotational speed compared with PA6; the density-related stress at a given angular velocity is approximately 11 % lower than PA6. This property is used in cable sheaves and indexing wheels where peripheral speed is limited by heat generation from hysteresis and friction rather than tensile strength.
If PA12 virgin resin is reprocessed into moulded components, pre-drying at 80 °C for 4 h to 6 h in a dehumidifying dryer to a residual moisture below 0.10 % is specified to prevent hydrolytic degradation. Melt temperature measured at the nozzle is commonly limited to 190 °C to 230 °C; barrel zones are profiled from 180 °C at the feed throat to 220 °C at the metering zone. Mold temperature is controlled at 30 °C to 60 °C, with lower mold temperatures yielding faster cycle times but higher frozen-in stress. Holding pressure and gate size must be matched to the low melt viscosity; excessively high shear can cause material yellowing.
In cam-driven guide rails in bottling lines, the component is machined from natural Murdopol Nylon 12 with a slot width of 12.00 mm to 12.03 mm; the rail is conditioned before final polishing to avoid field expansion closing the slot below the cam follower diameter. The material is selected over PA6 when the line alternates between dry cold seasons and chlorinated alkaline washdown. Wear life in such low-pressure sliding applications is governed by contact pressure and surface finish of the steel cam follower; hardened stainless steel with roughness below Ra 0.4 µm is generally specified. The unfilled nylon 12 surface can be polished to Ra 0.2 µm to 0.4 µm by diamond turning or burnishing. If abrasive filler is present in process water, unfilled PA12 wears more rapidly than PA6 MoS₂-filled grades; in that case the replacement is not mechanically equivalent despite the moisture and impact advantages.
