Large CNC Machining — Big Parts & Heavy Components

What we machine on this process

Large CNC machining covers parts that exceed our standard 800 × 500 mm milling envelope — base plates, machine frames, mounting plates, weldments that need post-machining, large flanges and structural brackets. The work splits two ways: we machine in-house up to the 800 × 500 mm envelope, and oversized parts are quoted on the same drawing through our vetted partner network, managed under one quality process, rather than refused. Because large work is usually a mix of milling, drilling and tapping on a heavy part, planning matters more than raw size: we decide the datum faces, the clamping strategy and the cutting sequence before metal is cut, so a large part stays square through every setup.

Materials and finishes

Large parts are usually aluminium or steel. We machine aluminium 2024, 5052, 6061 and 7075; stainless steel 301, 303, 304, 304L, 316, 316L, 410, 416 and 17-4PH; carbon and alloy steel 1045, 1215, 4140, D2 and O1; plus brass, bronze, copper and titanium where weight or corrosion matters. On large aluminium plates the trade-off is weight against rigidity; on steel, weldments are often machined after welding to true up the critical faces. See the grade list on our materials page. Finishes for large parts — anodizing for aluminium, passivation or plating for steel and stainless — are arranged through our vetted partner network, managed under one quality process, and sized to the part.

Size, tolerance and capacity limits

Our own milling envelope is 800 × 500 mm. Parts beyond that are quoted through our vetted partner network on the same drawing, so you still get one quote, one contact and one set of documents. Precision features are held to ±0.01 mm and general tolerances follow ISO 2768-m unless stated on the drawing, although on a long part the practical tolerance is governed by how the part is clamped and how it moves as material is removed. That is why large parts are often split into sub-assemblies: several smaller, easier-to-hold pieces bolted together are cheaper and more stable than one oversized monolith, and each sub-part can be machined within the envelope. We raise this split at the DFM stage if it lowers your cost.

Documents and shipping

Large work is machined and dispatched from our factory in Qidong City, Jiangsu Province, China, with oversized steps run through our vetted partner network under the same process. Every batch ships with a material certificate (MTR) and pre-shipment photos of your actual parts, so you can confirm the grade and see how the finished piece was packed before it leaves. Lifting and blocking for transport are planned into the job rather than left to the courier, and one contact handles the order from drawing to delivery.

Industries we support

Large machined parts appear wherever a machine needs a rigid backbone. Base plates and frames serve agriculture, hydraulic and pneumatic and general automation; large flanges and manifolds feed oil and gas and marine; and structural brackets and housings show up in automotive and electronics. Oversized work is quoted on the same drawing through our partner network, so a sector that needs big parts is not turned away. See our industries hub for the full list.

Design guidelines for cost and manufacturability

Design large parts around the machining sequence. Give the drawing a clear datum face and holes for clamping or lifting, so the part is located the same way in every setup; a part that must be re-clamped without a datum drifts out of tolerance. Keep tolerances realistic across a long span — a tight ±0.01 mm feature is far cheaper on a small boss than across a metre-long frame, so apply the tight figure only where the function needs it and leave the rest at ISO 2768-m. Consider splitting one big part into bolted sub-assemblies: smaller pieces are easier to hold, cheaper to transport and simpler to replace if one is damaged. Avoid deep pockets in a tall wall where cutter reach is limited. Our DFM guide and drawing requirements pages cover these points in detail.