Castings & Forgings

Casting and forging routes we supply

Castings and forgings are the components where sourcing risk is highest, because internal defects are invisible on arrival and appear later as a field failure. VP Global Exim supplies both from India through foundries and forging shops selected for the specific process, alloy family and quality documentation each part requires, and we specify non-destructive testing appropriate to the application rather than relying on a visual inspection that cannot see the failure mode.

Casting routes include green sand and resin-bonded sand casting for medium and large components, shell moulding for better surface finish and dimensional accuracy on medium volumes, investment casting for complex geometry and fine detail in steel and stainless steel, gravity die casting for aluminium in medium volumes, high-pressure die casting for aluminium and zinc at higher volumes, and centrifugal casting for cylindrical sections. Casting weights range from a few hundred grams to several tonnes depending on the route and foundry.

Forging routes include closed-die drop forging for repeatable near-net shapes, open-die forging for larger and simpler geometry and for one-off items, upset forging for flanged and headed parts, ring rolling for seamless rings, and cold and warm forging for high-volume smaller components. Forgings are supplied in the as-forged condition, heat treated, or fully machined, according to your requirement.

Which route suits your part is a genuine engineering decision, and we discuss it rather than pushing the process a particular vendor happens to own. A part currently sand cast may be better investment cast if machining allowance is dominating cost; a part currently machined from bar may be far cheaper as a near-net forging at your volume. We put the comparison in front of you with tooling cost, piece price and lead-time consequences stated.

Alloys, chemistry and mechanical properties

Ferrous castings are supplied in grey cast iron across the standard strength grades, ductile or spheroidal graphite iron including as-cast and heat-treated grades, austempered ductile iron where wear and fatigue performance matter, carbon and alloy cast steels, stainless steels in austenitic, martensitic and duplex families, and wear-resistant high-chrome and manganese steels. Non-ferrous castings cover aluminium casting alloys, brass and bronze including leaded, tin and aluminium bronzes, and zinc alloys for pressure die casting.

Forgings are supplied in carbon and alloy steels including case-hardening and through-hardening grades, stainless steels, aluminium forging alloys, and brass and copper alloys. Where your drawing specifies a national or regional standard grade, we cross-reference to an available equivalent and present the chemical and mechanical comparison for your written approval rather than substituting on our own judgement.

Chemistry is verified on every heat by spectrometric analysis, and the result is recorded against the heat number and supplied with the shipment. Mechanical properties are verified on test bars or on samples taken from the casting or forging as your specification requires: tensile strength, yield strength, elongation, hardness, and impact toughness including low-temperature Charpy values where the application demands them. Where the specification requires properties measured on the component rather than on a separately cast test bar, we plan for a sacrificial part and price it accordingly.

Microstructure is examined where the grade depends on it. Graphite form, nodularity and nodule count on ductile iron, pearlite and ferrite balance, grain size, decarburisation depth on forgings, and inclusion rating are assessed by metallographic examination against the specification. On ductile iron in particular, nodularity is the property that determines whether a casting behaves as ductile iron at all, so it is measured rather than assumed.

Pattern, tooling and dimensional control

Tooling is where casting and forging programmes are won or lost. For castings we produce patterns, core boxes, match plates and dies to suit the route and volume, in wood, resin, aluminium or steel according to the expected life. For forgings we produce closed dies in tool steel with the appropriate flash land, draft and fillet design. Tooling design accounts for shrinkage, draft, machining allowance, gating and feeding, and parting-line placement, and we share the proposed layout with you before cutting metal.

Tooling cost, ownership and life are stated in the quotation. Where you pay for tooling, it belongs to you, is recorded against your programme, is maintained by us during the programme, and is released to you on request. We also state expected tool life in shots or pieces and what refurbishment will cost, because a low tooling price on a short-life tool is not a saving.

Dimensional control on castings and forgings is different from machining and needs realistic expectations. We work to the tolerance grades appropriate to the process, typically the ISO 8062 casting tolerance and required machining allowance grades for castings and the relevant forging tolerance standard for forgings, and we agree those grades with you at quotation. Where your drawing applies machined tolerances to as-cast features, we raise it as a query rather than accepting an order we cannot meet.

First-off castings and forgings are dimensionally verified against the drawing, including layout inspection on a surface plate or CMM, wall thickness verification by ultrasonic thickness measurement where access is limited, and machining allowance confirmation on every surface to be machined. Only after a first article is accepted do we release the tool for production, and any tool modification triggers re-approval.

Non-destructive testing and soundness

The defects that matter in castings and forgings are mostly internal: shrinkage porosity, gas porosity, inclusions, cold shuts and hot tears in castings; laps, bursts, flow-through defects and inadequate grain flow in forgings. None of these are visible externally, so we specify non-destructive testing according to the criticality of the part rather than treating testing as an optional extra.

Available methods include radiographic testing for internal soundness with film or digital imaging, ultrasonic testing for internal discontinuities and wall thickness, magnetic particle inspection for surface and near-surface defects on ferromagnetic materials, liquid dye penetrant inspection for surface defects on non-magnetic materials, and pressure and leak testing including hydrostatic and air-under-water testing on components that must contain fluid. Visual inspection is carried out against a written acceptance standard rather than by impression.

Acceptance criteria are agreed before production. A statement that a casting must be free from defects is not a usable specification, because every casting contains some level of discontinuity. We work to defined acceptance levels from the applicable standard, at a stated inspection zone and severity level, so the foundry, our inspector and your engineering team are all judging against the same threshold. This single step prevents most disputes over casting quality.

Repair policy is agreed rather than discovered. Some applications permit weld repair of castings under a qualified procedure with subsequent stress relief and re-inspection; others prohibit it entirely. We ask which applies at quotation, record it in the specification, and require the foundry to declare any repair. An undeclared repair is treated as a quality failure regardless of whether the repaired part would have been acceptable.

Machining, finishing and supply condition

Most buyers prefer to receive castings and forgings machined and ready to assemble rather than raw, and we supply either. Machining is carried out in the same supply chain on CNC turning and machining centres, with fixtures designed for the as-cast or as-forged datum surfaces. Because a casting's datum structure differs from a bar-turned part's, fixture design and first-operation datum selection are engineering decisions we make deliberately and document.

Where a part is supplied machined, the inspection scope covers both the casting or forging properties and the machined dimensions, and you receive both sets of evidence: chemistry and mechanical properties with the heat number, non-destructive test results, and the dimensional report on machined features. Buyers occasionally receive machined castings with a dimensional report and no metallurgical evidence at all, which leaves the most important properties undocumented.

Surface preparation and protection options include shot and sand blasting, grinding of parting lines and gate remnants, tumbling and vibratory finishing, primer and paint including two-pack systems, powder coating, hot-dip galvanising, zinc and other electroplating on suitable geometry, phosphating, and rust-preventive oil or VCI protection for transit. Where a casting will be painted by you on receipt, we agree the surface condition and any temporary protection so your paint process is not compromised.

Documentation and certification

The documentation pack is a substantial part of what you are buying. A standard casting or forging shipment leaves with a material test certificate stating chemical analysis and mechanical properties against the heat number, heat treatment certificates with furnace charts where treatment is specified, non-destructive test reports for each specified method with the acceptance standard and level referenced, dimensional inspection reports, and a certificate of conformity referencing the drawing revision.

Where your specification or market requires more, we arrange it: EN 10204 type 3.1 or 3.2 certification with third-party endorsement, third-party inspection and stage inspection by an agency you nominate, welding procedure and welder qualification records where fabrication is involved, positive material identification, and traceability from finished component back to melt with marking maintained through machining. Pressure-equipment and other regulated applications require specific documentation, and we confirm what is achievable before accepting the order rather than after.

Foundry and forge quality-system certification is disclosed rather than implied. We tell you which quality management certification the producing unit holds and whether it is current, and we support buyer audits and pre-production visits. Where a programme requires a specific approval that our supply base does not hold, we say so plainly instead of proceeding and hoping the question is not asked.

Cost, volume and programme planning

Casting and forging economics are dominated by tooling amortisation, material yield and machining allowance, and we make all three visible in the quotation. A high-pressure die-cast part carries substantial tooling cost and a low piece price; a sand-cast equivalent carries low tooling cost and a higher piece price with more machining. Which is right depends entirely on your annual volume and programme life, so we quote the realistic alternatives rather than one number.

Machining allowance is a hidden cost driver that buyers frequently overlook. A casting produced by a route with poor dimensional repeatability requires more allowance, which means more material, more machining time and a longer cycle. Moving to shell moulding or investment casting often reduces total cost even at a higher casting price, and we run that comparison when a part's machining content looks disproportionate.

For ongoing programmes we support blanket orders with scheduled call-off, agreed buffer stock at origin, and maintained tooling with planned refurbishment. Where material prices in your alloy are volatile, we can quote with a stated validity period and a transparent basis for revision rather than absorbing volatility into an inflated fixed price.

Getting a casting or forging quoted

To quote accurately we need the drawing with material specification, tolerances, machining allowance if the part is to be supplied raw, surface finish and protection requirements, and any non-destructive testing and acceptance standard. Annual and per-batch quantities matter as much as the drawing, because they determine the route and therefore the price. Where you have a sample part, sending it shortens the conversation considerably.

If you are currently importing the part from elsewhere and want a comparable source, tell us the current process route and any known issues in service. Recurring field failures usually point to a specific defect mechanism, and knowing it lets us specify the testing that would have caught it rather than reproducing the same part with the same weakness.

We will come back with a proposed route, tooling cost and ownership terms, piece price at your stated volumes, lead time for first article and for production, the testing and documentation scope, and any queries on the drawing that need your engineering team's decision. Nothing goes into production before a first article is accepted in writing.