Custom CNC Machined Parts | Feature Relationships

Name: Custom CNC Machined Metal & Plastic Parts
Brand: Goldcattle
SKU: CNC-44

Description

Custom CNC Machining · Metal & Engineering Plastics

Custom CNC Machined Metal & Plastic Parts

A machined part is not accepted because its dimensions are inside tolerance. It is accepted because the features that mate with something else are right relative to each other — the two holes that take a pin, the bore that has to be square to the face it seats on, the wall that must not move when the last clamp comes off. That set of relationships is what a drawing actually specifies, and it is what we machine to. This page is about the parts, the features and the evidence; the machines and the plant are on the services page.

Milled · turned · 5-axis
Aluminum · stainless · titanium · brass
PEEK · POM · PEI · PTFE · PA
CMM report · FAI · material certs

Upload Your Part Drawing What decides a feature →

Six part families, one review process. What separates them is not the material — it is which features have to be right relative to which other features.

ScopeParts machined to your drawing

FamiliesMilled, turned, multi-axis

MaterialsMetals and engineering plastics

EvidenceDimensional report, FAI, certs

What This Page Answers, and What It Hands Back

This page covers the part

Part families and what distinguishes them; which machining route a geometry actually needs; material grades and what each one does badly; the features that decide whether a part is holdable; how tolerance is stated per feature rather than per shop; what a design review changes; finish by substrate; the documents that come with an order; and how the same part behaves at one piece and at ten thousand.

It is written for the person who has to release a drawing and defend it afterwards: a design engineer, a manufacturing engineer or a sourcing engineer at an OEM that has the drawing and needs the part.

This page does not repeat the plant

Spindle hours, floor area, machine list, company history and process photography live on the CNC machining services page, because that is the page a buyer reads when they are qualifying a supplier rather than releasing a part. Repeating it here would make two pages compete for the same query and neither one better.

What this page keeps for itself is the engineering conversation that happens after the supplier is qualified and before the first chip is cut.

Question you actually have	Where it is answered
Does my geometry belong to a milled, turned or multi-axis family?	Below, on this page
Which material grade suits the load, the environment and the budget?	Below, plus the material library for full grade data
Which feature on my drawing is the one that will decide the price?	Below: the feature budget
How is tolerance stated, and what does ±0.005 mm apply to?	Below, plus the tolerance tables on the services page
What plant, equipment and capacity will make it?	CNC machining services
How is the part actually cut, step by step?	CNC milling and CNC turning

Four Part Families, Distinguished by Geometry Rather Than by Material

Part catalogues usually sort by material, which is the wrong axis for a buyer. Two aluminum parts can need completely different shops: a plate with a pocket on one face is a milling job, while a 300 mm shaft with three diameters, a thread and a cross hole is a turning job with a milling operation inside it. Sorting by geometry tells you what will actually be hard about your part.

Milled components

Prismatic parts: housings, plates, brackets, manifolds, covers. Features are pockets, slots, bolt patterns, tapped holes and open contours, cut from one direction where possible. The difficulty is almost never the outline — it is pocket depth against tool reach, and thin floors or walls that move when the part is unclamped.

Turned components

Rotationally symmetric parts: shafts, bushings, sleeves, spacers, threaded fittings, flanged pins. Features are diameters, grooves, threads, bores, chamfers and faces. The difficulty is diameter-to-length ratio, surface finish on a long unsupported section, and any feature that is not coaxial — a flat, a cross hole or a slot on a diameter turns the job into a second operation.

Multi-axis components

Parts with features on several faces, on inclined pads, or on a curved surface: angled ports, compound-angle holes, contoured bodies, impeller-like forms. The point of a fourth or fifth axis is not prestige — it is that the features keep their relationship to each other because they are cut without being released and re-clamped.

Engineering plastic components

Insulators, gears, bushings, seals, wear pads, fluid-handling blocks. Cutting is easy; holding is not. Plastics move after machining, absorb moisture, build internal stress when a skin is removed from one side only, and burr differently from metal — so the process has to be planned around the material's behaviour rather than around the cutter.

Four custom milled aluminum components: a mounting plate with a central pocket, lightening slots and a raised boss, an L-shaped bracket with filleted corner, a manifold block with parallel bores and cross-drilled ports, and a thin cover plate with an engraved pocket — Milled family. The manifold block is the instructive one: its difficulty is the intersection of the cross-drilled ports with the main bores, which is a burr and breakthrough problem, not a tolerance problem.

Feature in your design	What it makes the part	What it costs you
All features reachable from one face	A single-setup milled part	Nothing extra — this is the cheapest geometry there is
Features on two opposite faces	A two-operation milled part	A second datum to establish, and a position error between the faces that no single feature's tolerance describes
An inclined pad with holes	A 3+2 or 5-axis part	Either a fixture on an angle or a machine that tilts; the fixture is cheaper once, the machine is cheaper at volume
A hole on a curved surface	Multi-axis, or a drilled flat spot	The drill walks on a curved entry unless the surface is spotted first, and the exit breaks out unevenly
A cross hole in a turned part	A turn-mill part	A second operation, or a machine with live tooling; either way the position is now a two-axis relationship
A flat or slot on a diameter	A milled feature on a turned part	Orientation becomes a controlled dimension, and it has to be measured against the diameter, not the end face

Six stainless steel CNC turned components: a stepped shaft with a milled flat, a slender threaded shaft with a polished journal, a hex fitting with a cross hole, a flanged bushing, a thin-walled sleeve and a knurled collar — Turned family. The stepped shaft has a milled flat on its middle diameter — a two-line feature that quietly turns a pure turning job into a turn-mill job, because that flat has an orientation relative to something.

Which Route a Geometry Actually Needs

Buyers often ask for five-axis machining because they assume it is better. It is better only when the part has a feature that cannot be reached, or cannot stay in relationship, from a fixed three-axis setup. On a part where every feature is reachable from one face, five axes add nothing and cost more per hour. The table is the decision we actually apply at review.

Route	Trigger in the geometry	What it protects	When it is the wrong choice
3-axis milling	Every feature reachable from the top face; depth within tool reach	Cost and lead time; one setup, one datum	The moment a feature moves to a second face, the setup count — and the error — doubles
3-axis, multiple setups	Two or three faces, each simple	Simple geometry at low cost	Features with a mutual relationship across the faces: each face is accurate and the pair is not
4-axis, indexed	Cylindrical or wrapped parts with features at angles around an axis	The angular relationship between features around the axis	When the fifth face also has to be cut: the index is a rotation, not an orientation
3+2 (positioned 5-axis)	Inclined pads, compound-angle holes, a few tilted faces	Machining on an angle without a dedicated angle fixture	When the same setup also needs continuous simultaneous motion — positioned axes cannot follow a surface
Simultaneous 5-axis	Curved surfaces, deep contoured pockets, ports on a sculpted body	Surface continuity and a single datum across a curved form	Prismatic parts: the extra capability is paid for and not used
Turn-mill	A turned part with a cross hole, flat, slot or off-axis feature	The coaxial features and the off-axis feature in one clamping	Parts with no rotational symmetry at all — that is a milling job
EDM / wire EDM	Sharp internal corners, hardened material, thin slots a cutter cannot reach	Geometry a rotating tool cannot produce	As a substitute for a machining operation because of a design corner radius — changing the radius is cheaper
Grinding	Hardened parts, tight roundness or finish on a journal	Roundness, finish and size after heat treatment	Soft parts where milling or turning already meets the drawing

The rule behind the table. Every time a part is released and re-clamped, a new position error is created and the previous datum has to be re-established. A part with features on four faces made in four setups has four opportunities to drift; the same part made in two setups has two. This is why “can you hold the tolerance on this feature” is often the wrong question — the better one is “which features have to stay related, and can they be cut together”.

Five-axis machining center cutting a tilted aluminum component on a trunnion rotary table, with an end mill cutting an inclined face, coolant flowing and aluminum chips curling away — Trunnion machining of a part with an inclined pad. The pad, the pocket on the adjacent face and the holes in it keep their relationship because the table tilts rather than the part being moved.

Materials: What Each Grade Does Badly

Material tables usually list what a grade is good at, which is the part a buyer already knows. The useful column is the failure mode — because that is what turns into a rejected batch, a warped plate or a thread that strips on assembly. The grades below are the ones we machine routinely; full grade data sits in the material library.

Grade	Chosen for	Where it bites	Typical parts
6061-T6 aluminum	Machinability, corrosion resistance, anodizing response	Strength is modest; it galls against stainless threads and welds poorly after anodizing	Housings, plates, brackets, manifolds
7075-T6 aluminum	Strength and stiffness per gram	Notch sensitive, poorer corrosion resistance, cannot be welded, and hard anodizing reduces fatigue strength	Loaded structural parts, aerospace fittings
6082-T6 aluminum	European drawing convention; good strength with better forming than 7075	Less common off the shelf, so lead time can be longer than 6061	Structural parts, machine components
304 stainless	General corrosion resistance, food-adjacent equipment	Work hardens under a dull tool and starts to chatter; not chloride resistant	Shafts, bushings, fittings, housings
316L stainless	Chlorides, chemical exposure, medical and marine environments	Gummier to cut than 304, tends to smear and burr; low carbon grade is softer than people expect	Instrument parts, fluid fittings, marine hardware
Ti-6Al-4V	Strength-to-weight with corrosion resistance	Low thermal conductivity keeps heat in the cut, so tool life collapses without high-pressure coolant; springy, so thin walls deflect away from the cutter	Aerospace brackets, medical components
Brass C360	Free machining, conductivity, good threads	Lead content restricts some applications; dezincification in certain waters	Fittings, terminals, small precision parts
Carbon steel 1045	Strength at low cost	Corrodes immediately without a finish; machines well only in a consistent condition, so stock condition has to be stated	Shafts, pins, mechanical parts

Engineering plastic	Chosen for	Where it bites	Typical parts
PEEK	Temperature, chemical resistance, dimensional stability at temperature	Expensive per kilogram, so stock size and scrap matter; benefits from an annealing step before finish machining	Insulators, high-temperature bushings, fluid parts
POM (acetal)	Dimensional stability, low friction, good machinability	Internal stress in extruded bar releases when a skin is removed, so a thin section can bow hours later	Gears, bushings, wear pads
PEI (Ultem)	Heat resistance, electrical insulation, transparency in thin sections	Notch sensitive and brittle; sharp internal corners become cracks under load	Insulating covers, electrical components
PTFE	Lowest friction, broad chemical resistance	Cold flows under sustained load, so a press fit relaxes; very soft, so holding it without marking is the machining problem	Seals, rings, insulating parts
PA6 / PA66 nylon	Toughness, wear resistance, impact strength	Absorbs moisture and grows; a part machined dry to a tight tolerance may not fit after a week in a humid warehouse	Gears, rollers, mechanical parts
ABS	Cost, impact resistance, machinability	Low stiffness and heat resistance; solvent and UV sensitive	Housings, covers, prototypes

Three material rules that come up on nearly every project. Aluminum plate is not stress free. A part machined from the middle of a thick 6061 plate can bow after the clamps come off, because removing material releases the balance inside the plate; a stress-relieved grade, or a rough-and-finish sequence with a pause between, is cheaper than tightening the flatness call on the drawing. Lock the condition, not just the grade. “6061” does not define a temper, and “1045” does not define whether the bar arrived annealed or normalized. Plastics need to be machined in the condition they will live in. A nylon part dimensioned to a tight tolerance, machined from dry stock and shipped into a humid plant, will be a different size on arrival.

Five CNC machined engineering plastic components: a beige PEEK insulator block with a slot, a white POM gear blank with keyway, a black flanged POM bushing, an ivory PTFE ring seal and a translucent amber PEI cover — The plastic family. Each of these five behaves differently after machining: PEEK wants an anneal, POM releases stress when skinned, PEI cracks at a sharp internal corner, PTFE creeps under a press fit, and nylon grows as it takes up moisture.

The Feature Budget: Which Call on the Drawing Decides the Price

Every part has one or two features that set its cost, and they are rarely the features the designer worried about. This table is the one we use to explain a quotation, because it maps a drawing dimension to the physical reason it is hard — and to the cheapest honest way to make it easier.

Feature	What makes it hard	Practical limit worth designing to	Cheaper alternative
Thin wall	The wall deflects away from the cutter, then springs back and is cut oversize; clamping closes it before the cut	Wall height to thickness ratio is the number that matters, not thickness alone	Add a rib, reduce wall height, or accept a rougher finish on the non-functional face
Deep pocket	Tool reach: a cutter long enough to reach the floor is thin enough to chatter	Pocket depth against cutter diameter, roughly four to five times diameter before it gets expensive	Widen the pocket base, change the corner radius, or accept a stepped floor
Sharp internal corner	A rotating cutter leaves its own radius; the corner cannot be sharper than the tool	Corner radius at least equal to a standard cutter radius for the pocket depth	Specify a radius, or move the corner out of the load path
Deep or small hole	Drill wander and chip evacuation; length-to-diameter ratio governs both	Beyond roughly five times diameter, hole position and straightness both degrade	Drill from both sides, use a larger diameter, or accept a position tolerance that reflects the depth
Thread near an edge	The wall around the thread is thin and the minor diameter is close to the outside face	Engagement length and wall thickness around the thread, not the thread call itself	Move the thread inboard, add a boss, or use an insert
Flatness on a thin plate	Release of internal stress and clamping distortion, not the machining	Flatness over the part's longest dimension, referenced to how it is supported	Stress-relieved stock, or a rough-and-finish sequence with a pause
Concentricity over a long overhang	Deflection of the workpiece or the tool between supports	Length to diameter of the feature, and whether a steady or tailstock is used	Reduce overhang, add a center, or split the feature into two shorter ones
True position on a bolt circle	Every hole is dimensioned from a center that has to be established first	Hole count and circle diameter; more holes at the same tolerance cost more inspection time	Use a positional tolerance with a maximum material condition bonus where the function allows
Surface finish on a bore	Reach, tool rigidity and the finish left by the last pass	Ra achievable falls as bore depth and diameter ratio worsen	Specify finish only on the sealing or bearing length, not the whole bore

Two conclusions follow, and both are worth raising before a drawing is released. First, tolerance is not free but it is not the main cost either — the number of setups, the number of features and the amount of material removed usually dominate. Second, the cheapest drawing change is almost always a radius, a wall thickness or a hole position, and the most expensive is a flatness or concentricity call added “to be safe” on a feature that carries no load.

Tolerance: A Number per Feature, Not a Number per Shop

The most misleading thing on a machining website is a headline tolerance. “±0.005 mm” printed on a page, without saying which features on which material at which size, is a promise nobody can keep across a catalogue — and a buyer who plans around it will eventually be disappointed by a part that was made correctly. We publish the capability, then we qualify it in the same breath.

How we state it. Tolerances as tight as ±0.005 mm can be evaluated for suitable machined features, depending on the material, the geometry, the part size and the inspection method. It is not a blanket figure for every dimension on every part, and it is not applied to a feature that cannot be measured to that level anyway. On any real drawing, the tight call is normally confined to two or three features; the rest is general tolerance, and quoting the whole part to the tightest number would only make it expensive.

What the drawing specifies	How it is normally stated	What makes it achievable
Linear dimensions	General tolerance block, plus individual calls on critical lengths	Datum scheme and whether the dimension crosses a setup
Hole diameter and position	Diameter with a limit, position as true position from stated datums	Boring or reaming after drilling, and cutting related holes in one setup
Threaded features	Thread standard and class, depth, and the face it starts from	Whether the thread is cut or formed, and the wall around it
Flatness	On a named datum face, with the support condition understood	Stress-relieved stock, sequence, and how the part is rested when measured
Parallelism / perpendicularity	Relative to a datum that is actually machined	Cutting both faces in one setup, or measuring the relationship rather than the faces
Concentricity / runout	On rotating features, referenced to an axis	Turning between centers, or a single clamping
Surface roughness	Ra on named surfaces only	Finishing pass, tool condition, and access to the surface
GD&T profile	Profile of a surface against a full datum reference frame	Simultaneous multi-axis cutting, and a CMM program that reproduces the same frame

The measurement has its own tolerance, and it is not the part tolerance. A CMM in a temperature-controlled room can resolve far finer than most parts need, and that capability says nothing about what a milling machine can hold on a thin wall. The two numbers to keep separate are the instrument's uncertainty and the process capability on that feature; a report that shows a dimension at the edge of tolerance is telling you about the process, not about the CMM.

There is also a geometric trap worth knowing about, because it changes how a tolerance should be written. A position tolerance quoted as a diameter defines a circular zone; a tolerance quoted as plus-or-minus defines a square one. The square's corners lie outside the circle, so a part can pass a ±0.05 reading and still fail a Ø0.1 position requirement. If the function is “the pin must pass”, specify the circular zone and let the machinist and the inspector work to the same shape.

What a Design Review Actually Changes

Design for manufacturability is often sold as a checklist. In practice it is a short list of decisions that change the route, the price or the risk, and it is only useful if it happens before the program is written. These are the eight we raise, in the order they matter.

Check	What we look for	What we propose
Datum scheme	Whether the drawing's datums are machinable faces, or whether they are theoretical	A datum that exists after the first operation, and a callout that follows it
Setup count	Features that force a second or third clamping	Reorient the part, or accept a 4th-axis index, so related features are cut together
Wall and floor thickness	Ratio of wall height to thickness; floor under a deep pocket	A rib, a shallower pocket, or a rough-and-finish sequence with a stress-relief pause
Tool access	Pocket depth against cutter diameter; corner radii smaller than a standard cutter	A larger corner radius, a wider pocket base, or a stepped floor
Hole design	Length-to-diameter, breakout on a curved surface, holes breaking into each other	Spot-face the entry, drill from both ends, or accept a realistic position tolerance
Threads and inserts	Thread depth against hole depth; wall thickness around a thread	Deeper engagement without a through wall, or a threaded insert where the substrate is soft
Material condition	Whether the grade, temper, form (plate, bar, extrusion) and stress state are stated	A specific condition, and stress-relieved stock where flatness matters
Finish compatibility	Whether the specified finish suits the substrate, and what it does to dimensions	An alternative finish, or a pre-finish allowance on features that must stay in tolerance

The honest version of “we improved the design”. A review that says “we optimised the part and reduced cost by 30%” without saying what changed is marketing. What a review can state precisely is what it changed and why: a corner radius opened from 1 mm to 3 mm so a standard cutter reaches the floor; a pocket depth reduced by 4 mm to stay inside a stable length-to-diameter; two faces combined into one setup so the bore and the mounting face stay square. Those are the sentences worth putting on a page, and they are the ones we ask a customer to confirm before quoting them.

Surface Finish, Chosen Against the Substrate

Finish is where a machining quotation most often changes after the fact, because the finish a buyer names is sometimes incompatible with the material, or changes a dimension that was toleranced before it was chosen.

Substrate	Finishes normally applied	What it does to the part	What to watch
Aluminum	As-machined, bead blasting, Type II anodize, Type III hard anodize, chromate conversion, powder coat	Anodize adds 10–25 µm per surface (Type II) or 25–50 µm (Type III) and grows both outward and inward, so a bore closes by twice the film	Mask threads and bores that must stay in tolerance; hard anodize reduces fatigue strength on a loaded part
Stainless steel	As-machined, bead blasting, passivation, electropolishing, mechanical polishing	Passivation removes free iron and does not move dimensions; electropolishing removes material, so bores grow and edges round	Do not tolerance a bore and then electropolish it without an allowance
Carbon steel	As-machined, black oxide, zinc or nickel plating, powder coat	Plating adds a film of a few to tens of micrometers; black oxide barely moves dimensions	Hydrogen embrittlement risk on high-strength plated parts; edges plate differently from faces
Brass	As-machined, polishing, plating, bead blasting	Cosmetic improvement; plating builds on threads	Soft substrate marks during handling; specify protection for visible faces
Titanium	As-machined, bead blasting, polishing, specified anodizing	Anodizing on titanium is a thin oxide, largely cosmetic and dimensional-neutral at normal thickness	Color is process-dependent; a physical sample is a better reference than a color name
Engineering plastics	As-machined, deburring, tumbling, polishing, laser marking where specified	No coating in most cases; finish is a cutting result	Solvent-based cleaners can craze PEI and polycarbonate; a machined finish is the honest spec

Four identical aluminum test coupons in a row showing different finishes: bare as-machined with visible cutter marks, uniform bead-blasted matte, satin clear anodized, and deep matte black anodized — The same part, four finishes. Left to right: as-machined, bead blasted, clear anodized, black anodized. Only the second and third are interchangeable on a dimension that matters — anodizing moves the surface, and a bore closes by twice the film.

Inspection, and the Documents That Come With It

“100% inspection” is a sentence that means nothing until it says which characteristics were measured, against which drawing revision, with which instrument. What we can commit to is narrower and more useful: the characteristics that affect fit and function are measured and reported, and the document set is agreed at quotation rather than discovered at shipment.

Document	What it proves	What it does not prove
Material certificate	The grade and heat number of the stock that went into the part	That the finished part meets the drawing — a correct material can still be machined wrong
Dimensional inspection report	The measured values of the characteristics in the agreed plan	Anything outside that plan, and anything not measurable with the method used
CMM report	Position, form and orientation against a stated datum frame	A capability claim on a feature the CMM was not programd for
First article inspection (FAI)	That the first part of a run was verified against the drawing in full	That every subsequent part is identical — that is process control, not FAI
Surface roughness record	Ra on the surfaces that were measured	Finish on a surface the instrument could not reach
Visual / cosmetic record	That the agreed cosmetic criteria were checked	Subjective acceptance criteria that were never written down

Two standard numbers cause more confusion than any other on a purchase order, and neither is a machining certification. AS9102 is the aerospace standard for the format and content of a first article inspection report: it tells you how an FAI is documented, not that a shop is approved to make aerospace parts. EN 10204 3.1 is a type of material inspection certificate, issued by the mill or by the stockholder with traceability to the heat: it describes a document, not a product certification. Our quality management system is certified to ISO 9001:2015; anything beyond that is agreed per project and, where a customer's industry requires a certified special process, resolved at supplier approval rather than implied on a web page.

Coordinate measuring machine with a ruby stylus inside the bore of a machined aluminum housing on a granite table, with a second identical part and a gauge block beside it — Bore, position and form measured from a stated datum. The report is only as meaningful as the datum frame in it — a CMM aligned to a different frame than the drawing's is measuring a different part.

One Piece and Ten Thousand: What Actually Changes

Buyers often ask for a prototype price and a production price in the same enquiry, then find the two numbers hard to compare. They are different products, because the work behind them is different. Below is what changes at each stage — and, importantly, what does not.

Stage	What the buyer needs from it	What we do differently	What does not change
Single prototype	To prove the design and hold it in their hand	Program and setup spread over one part; stock may be cut from plate or bar rather than ordered to size	The drawing review — a prototype made to a weak drawing proves the wrong thing
Engineering validation	To test function, fit and life	Material condition and finish become fixed, because a finish can change a fit	Datum scheme and critical features
Low-volume production	A first batch for a customer build	Fixture and soft jaws justified; first article inspected and reported	The measurement plan
Pilot production	To prove the process before committing tooling	Process frozen, in-process checks added, stock size and supplier settled	Program and fixture, which now have to be controlled documents
Repeat production	Consistency across orders	Program, fixture and inspection plan held against the drawing revision; changes to any of them treated as a change	The revision the part is made to — unless the customer issues a new one

What makes a part cheaper at volume is not the machine getting faster. It is that the setup, the program, the fixture and the first-article inspection are paid for once instead of per piece, and that stock can be ordered in the right size instead of cut from a larger one. What makes it dearer at volume, unexpectedly, is a drawing that was never frozen: a revision that arrives mid-run invalidates the program, the fixture and the inspection plan together.

Revision control is a manufacturing cost, not an admin detail. A part number should mean one drawing revision at a time. When two revisions of the same part number are in circulation, the shop can produce a correct part that will not fit, and nobody can tell from the paperwork which one was made. Before a repeat order, state the revision on the purchase order; if it changed, send the new one and expect a re-review rather than a re-run.

What the Drawing Has to Carry, and How Confidentiality Is Handled

A 3D model defines the shape; it does not define what is acceptable. The drawing does that, and a drawing that omits the items below will always be resolved by somebody's assumption — usually the shop's, which is the wrong party to be deciding it.

Item	Why it is not optional
Revision and part number	The only way a shop and a customer can be sure they are discussing the same geometry
Datum reference frame	Position, orientation and form are all meaningless without it, and the CMM alignment depends on it
General tolerance block	Without it, every untoleranced dimension becomes a negotiation
Critical characteristics flagged	So the inspection plan can be built around the two or three features that actually decide acceptance
Material grade, temper and form	Plate, bar and extrusion behave differently; temper decides strength and machinability
Finish, and the surfaces it applies to	A finish named without a scope will be applied to threads it should not touch, or skipped on an interior face
Quantity and expected repeat	Decides fixture investment and stock strategy, which is most of the price difference between one and a thousand
Thread standard and class	“M6” is not a specification; the class and depth are

On confidentiality: drawings arrive under whatever arrangement the customer needs. We work under NDA on request, keep files inside the project rather than in open circulation, and treat a drawing revision as a controlled document — the shop floor works from the released revision, not from a photograph of a screen. If your IP process requires a specific handling statement, say so with the enquiry and it becomes part of the quotation rather than a discussion after the order.

Frequently Asked Questions

Can you machine parts directly from a STEP file?

Yes, provided the STEP file is accompanied by a dimensioned drawing. The model defines the shape; the drawing defines what is acceptable — datums, general tolerance, which characteristics are critical, the material condition and the finish scope. Files arrive as STEP, IGES, X_T, DXF, DWG or PDF, and a named revision is part of the submission. Where only a model exists, we will export the views and dimensions we intend to work to and send them back for confirmation before quoting, because a part made to an assumed tolerance is a part made to the wrong tolerance.

What is the difference between CNC milling and CNC turning for my part?

Milling cuts a stationary workpiece with a rotating tool and suits prismatic parts: plates, housings, brackets, manifolds, pockets and bolt patterns. Turning rotates the workpiece against a stationary tool and suits rotationally symmetric parts: shafts, bushings, sleeves, flanges and threads. The practical test is whether the features are coaxial. The moment a turned part needs a cross hole, a flat on a diameter or an off-axis slot, it becomes a turn-mill or a milled part, because that feature has to be cut in a second operation or with live tooling, and its position then becomes a controlled relationship rather than a free dimension.

Which materials can be CNC machined for industrial components?

Metals routinely machined here include 6061-T6, 7075-T6 and 6082-T6 aluminum, 304 and 316L stainless steel, Ti-6Al-4V titanium, C360 brass and 1045 carbon steel. Engineering plastics include PEEK, POM, PEI, PTFE, PA6 and PA66, and ABS. Each behaves differently after cutting: aluminum plate can release stress and bow, 316L tends to smear and burr, titanium keeps heat in the cut, POM moves when a skin is removed, nylon grows as it absorbs moisture. The grade is only half the specification — the temper, the stock form and the stress condition belong on the drawing too.

What tolerances can you achieve on machined parts?

Capability is stated per feature rather than as one figure for the shop. Tolerances as tight as plus or minus 0.005 mm can be evaluated for suitable machined features, depending on the material, the geometry, the part size and the inspection method. On a typical drawing that call is confined to two or three features that mate or locate; the rest is general tolerance. It is also worth separating two numbers that are often confused: a coordinate measuring machine can resolve far finer than a milling process can hold on a thin wall, so the instrument's capability is not a statement about the process.

Is 5-axis machining necessary for complex metal components?

Only when the geometry creates a need. Five axes earn their cost when features cannot be reached from a fixed setup, or when they must keep their relationship to features on another face and therefore have to be cut without releasing the part. A prismatic bracket with everything reachable from one face does not benefit; it simply costs more per hour. The decision we apply at review is whether the number of setups can be reduced, because every re-clamping creates a new position error and forces the datum to be re-established.

Can you produce both a single prototype and a production run of the same part?

Yes, and the two are quoted differently because the work behind them differs. At one piece, the program, fixture and setup are spread across a single part. At volume, those costs are amortised and stock can be ordered in the right size instead of cut from a larger one. What does not change is the drawing review, the datum scheme or the inspection plan — and what most often makes a production run go wrong is a drawing revision arriving mid-run, because it invalidates the program, the fixture and the inspection plan together.

What information do you need to quote a CNC machining project accurately?

A 3D model at a named revision, a dimensioned 2D drawing with the datum scheme and general tolerance block, the material grade with its temper and stock form, the quantity and expected repeat, the critical characteristics, the finish and the surfaces it applies to, and the documents you need with the shipment. Missing items are not fatal — they become assumptions, and assumptions are what turn into change orders, so the review names them before quoting rather than after.

How are machined parts inspected before shipment?

Against an agreed plan rather than a slogan. The characteristics that affect fit and function are measured and reported: critical dimensions, hole position and diameter, threads, form and orientation against the drawing's datum frame, and surface finish on named surfaces, plus a visual check against agreed cosmetic criteria. Depending on the project the document set includes a dimensional inspection report, a CMM report, a first article inspection report, material certificates and a batch record. Coverage is agreed at quotation, so the report that arrives matches the report that was promised.

What is the difference between a material certificate, EN 10204 3.1 and AS9102?

They are three different kinds of document and none of them is a machining certification. A material certificate states the grade and heat of the stock that went into the part. EN 10204 3.1 is a specific type of material inspection certificate, issued with traceability to the heat by the mill or stockholder — it describes paperwork, not product approval. AS9102 is the aerospace standard for how a first article inspection report is formatted and populated; it governs the report, not the supplier's approval to make aerospace parts. Our management system is certified to ISO 9001:2015, and any further scheme requirement is resolved at supplier approval for the specific project.

Which surface finishes are available for aluminum and stainless steel parts?

Aluminum takes as-machined finish, bead blasting, Type II anodize, Type III hard anodize, chromate conversion and powder coating. Stainless takes as-machined finish, bead blasting, passivation, electropolishing and mechanical polishing. The choice matters dimensionally: anodize builds 10 to 25 micrometers per surface in Type II and closes a bore by twice the film, while passivation removes free iron without moving dimensions and electropolishing removes material, so a bore grows and edges round. Threads and bores that must stay in tolerance are masked, and that decision belongs on the drawing.

How can I reduce the cost of a CNC machined part?

Usually by changing geometry rather than tolerance. The three changes that most often move a price are reducing the number of setups so related features are cut together, opening an internal corner radius to a standard cutter size so a stiffer tool can reach the floor, and keeping pocket depth within a stable ratio to cutter diameter. After those, the flatness and concentricity calls added for reassurance on features that carry no load are worth reviewing, and stress-relieved stock is usually cheaper than a tight flatness requirement on a thin plate.

How are customer drawings and intellectual property handled?

Drawings are handled under NDA on request, files are kept within the project rather than in open circulation, and a drawing revision is treated as a controlled document: the shop floor works from the released revision rather than from a copied image, and a change is registered rather than absorbed. If your process requires a specific handling statement or a security questionnaire, send it with the enquiry and it becomes part of the quotation. Manufacturing access is limited to what the part requires — the people who program and inspect it.

Send the Drawing, the Model and the Revision

STEP or IGES with a dimensioned PDF, the material grade and condition, the quantity you expect, the critical features, the finish and the documents you need. The review comes back with the route we would take, the features that will decide the price, and anything on the drawing that cannot be made or cannot be measured as called — before a program is written.

Upload Your Drawing and Request a Quote

STEP · IGES · X_T · DXF · DWG · PDF · NDA on request

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Xiamen Goldcattle Plastic & Metal Products Co., Ltd. machines custom metal and engineering plastic components to customer drawings on 3, 4 and 5-axis CNC equipment, with turning, milling, EDM and grinding routes, anodizing, passivation, plating, blasting, polishing and powder coating, and dimensional inspection including CMM, first article inspection and material certification, under an ISO 9001:2015 quality management system with project-level controls applied per order. Tolerances stated on this page describe capability that is evaluated per feature, per material and per part size at drawing review; they are not a blanket guarantee for any dimension on any part. Certification claims beyond ISO 9001:2015 — including aerospace, medical or automotive scheme approvals — are resolved at supplier approval for the specific project and are not implied by this page. Material grades, stock condition, finish systems and inspection scope are confirmed per project.