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RFQ Checklist for Custom OEM Aluminum Die Casting Parts

By HSX DIECASTING · September 6, 2026

How to prepare drawings, quantities and machining requirements for a useful quotation.

A useful request for quotation (RFQ) for an aluminum die-cast part should answer three questions: what the part needs to look like, what requirements it must meet at delivery, and how many parts you plan to purchase. An appearance photo or a part weight alone is usually not enough to establish the full cost of tooling, machining and surface finishing.

You can start a discussion before every detail is finalized. Separate confirmed requirements from targets and open questions so HSX can first assess whether the project is suitable, then identify what is still needed for a formal quotation.

Start with Three Types of Information

• Part information: Send the available 2D drawing, 3D model, sample details or clear photos. Include the drawing revision, units and approximate overall dimensions.
• Application requirements: Explain where the part is used, what it assembles with, and any confirmed material, critical dimension or surface requirements.
• Purchase plan: State the first-order quantity, expected repeat demand and target timing. Clarify whether you need raw castings or parts with machining and surface finishing completed.

If an item is still open, mark it as “to be reviewed.” This helps distinguish an initial manufacturing assessment from a formal quotation and prevents assumptions from being treated as final requirements.

Drawings and Samples: Mark the Critical Requirements

A 2D drawing communicates dimensions, tolerances, threads, material and technical requirements. A 3D model helps explain internal geometry, changes in wall thickness and machining locations. Where available, send both a 2D drawing and a STEP/STP 3D model. A model without explicit engineering annotations cannot, by itself, replace critical dimensional and acceptance requirements.

Identify the part number, revision and units in the files. If the drawing and model conflict, confirm which version governs. Do not resolve the difference simply by relying on a screenshot or the order in which files were sent.

• Assembly interfaces: Mark mounting holes, locating faces, mating bores, threads and sealing contact surfaces, and identify the corresponding mating parts.
• Dimensional requirements: Identify critical dimensions and state whether they apply to the raw casting, the machined part or the part after surface finishing.
• Appearance zones: Distinguish visible surfaces from non-cosmetic areas. Flag any requirements for parting lines, ejector marks or gate-removal locations in advance.

If local design changes can be considered, identify their permitted scope. Any change to dimensions, material or geometry must be approved by the customer before it becomes part of the tooling or production specification.

Quantities: Separate the First Order from Repeat Demand

“How many parts are needed now?” and “How many may be purchased later?” are separate questions. A trial order, scheduled repeat batches and a one-time purchase can lead to different tooling plans, production batches, fixture investments and quotation conditions. If annual demand is uncertain, provide an estimated range and label it as a forecast rather than a confirmed order.

Tooling cost should not be assessed from the first batch alone. For expected repeat production, tool material, design, maintenance arrangements and service requirements need to be considered together. For a small one-time requirement, first assess whether investing in a die casting mold is economical. Quantity alone does not determine the appropriate tool steel.

List the first-order quantity, expected quantity per batch, reorder frequency, projected repeat demand and whether the design may still change. HSX assesses the manufacturing plan against the actual geometry and requirements; no single quantity threshold makes every project suitable for die casting.

Material and Application: Identify the Fixed Requirements

If an alloy grade and standard are specified, provide them as stated in the drawing or technical documentation, and explain whether alternatives may be evaluated. Different grades are not interchangeable simply because they are all aluminum. A grade used for another manufacturing process should not automatically be treated as a suitable die casting alloy.

If the material is still open, describe the application, loading and assembly conditions, operating temperature, service environment, and any thermal conductivity, electrical conductivity or appearance requirements. HSX can use this information to discuss possible material options. The final choice remains subject to manufacturing review and customer approval.

For parts with sealing, corrosion protection or other performance requirements, specify the verification method and acceptance criteria. Terms such as “waterproof,” “corrosion-resistant” or “heat-resistant” alone do not provide a sufficient basis for quotation and acceptance.

Surface Finishing: Specify More than the Color

A black finish could be powder coating, spray painting, electrophoretic coating (e-coating) or another process. A photo alone usually cannot reliably identify the process, coating requirements or pretreatment route. If the finish must match an existing part, provide the original specification or a reference sample, then confirm whether further testing is needed.

Include the following in the RFQ:

• Appearance: Color, gloss, texture and the sample or approved standard to be used for comparison.
• Function: State whether the finish primarily serves appearance, corrosion protection, electrical grounding, insulation or another purpose. Describe different requirements separately.
• Process: Identify the specified finishing method. If it is undecided, mark it as “to be reviewed jointly against the application.”
• Masking and dimensions: Identify any threads, mating bores, contact faces or assembly surfaces that must remain uncoated, and mark the boundaries.

A coating changes the finished surface and may affect holes, threads and mating features. Confirm whether each area requires masking or may be coated based on its function. Do not assume that every hole must remain uncoated or that all surfaces need the same treatment. Any special coating thickness, adhesion or corrosion test requirements should also be defined before quotation.

Secondary Machining: Small Features Can Change the Cost

The cost of an aluminum die-cast part depends on more than its weight. A deep hole, a difficult-to-access thread or a surface requiring several machining setups can materially change the process and quotation. Highlight the following features on the RFQ drawing.

Small-Diameter Deep Holes

Specify the diameter, depth, direction and location requirements, and explain whether the hole is for a pin, locating, venting or another function. Small-diameter deep holes may require dedicated tools, fixtures or outside machining support, so they should not be priced as ordinary drilling without review. If the connection method or local geometry can change, alternatives can be evaluated. If the original design must be retained, feasibility and cost need to be assessed against that requirement.

Threads and Mating Surfaces

Specify the thread size, pitch and usable thread depth, and whether the hole is blind or through. Hole depth is not the same as usable thread depth. For mating bores and mounting faces, also define tolerances, surface condition and inspection datums so the quotation covers the final assembly requirements, not just hole creation.

Holes and Machined Faces in Multiple Directions

Hole direction, tool access, workpiece location and the number of setups affect the machining plan. Thin walls, deep cavities and areas susceptible to clamping distortion should be reviewed against the drawing. The quotation scope should identify which operations can be completed in-house and which require partner support.

How to Proceed with Incomplete Information

If You Only Have a 2D Drawing

Send the complete drawing and technical requirements first. HSX can review the dimensions, geometry and project scope, then identify any 3D data needed for complex surfaces, internal features or manufacturing assessment. A 3D model is not required just to begin the discussion.

If You Only Have a Sample or Photos

Photos can support an initial assessment of the part type. Include clear views of the outside, inside and critical interfaces, together with dimensions and the application. Hidden geometry, tolerances, material and surface treatment may still require drawings, a physical sample and other verification information.

Confirm the receiving arrangements before sending a sample. The customer covers sample shipping costs. If measurement or modeling is needed, agree on the scope, cost and deliverable requirements. Measurements from one sample do not automatically establish the original design tolerances or acceptance criteria for production batches.

If the Material or Finish Is Undecided

Describe the functional targets, service environment and any sample that must be matched, and list the open items. An initial discussion can proceed. A formal quotation should identify the proposed route, assumptions and exclusions, while tooling and production must follow the requirements ultimately approved by both parties.

Define the Delivery Scope and Acceptance Requirements

Clarify whether you need raw castings, drilled and tapped parts, or finished parts with surface treatment, inspection and packing completed. When comparing suppliers, check that mold, fixture, machining, finishing, inspection, packing and transport costs are quoted on the same scope.

• Inspection requirements: Identify critical dimensions, appearance reference samples, sampling or 100% inspection requirements, and any reports you expect. The ability to meet each item needs to be confirmed.
• Sample approval: If samples are required, state their validation purpose, quantity and the features to be approved. Initial form or fit checks do not replace validation of the production process and batch consistency.
• Timing: State the desired dates for receiving the quotation, approving samples and receiving the first batch. The actual schedule is confirmed after assessment.
• Packing and delivery: Specify any scratch protection, dividers, individual packing or labels, together with the delivery destination and transport scope.

Before mold manufacture or production, confirm the governing drawing revision, material, critical interfaces, surface and masking requirements, inspection criteria and packing method. Reference photos and unapproved notes from the RFQ stage should not automatically become production specifications.

An RFQ Checklist You Can Copy

Copy the following items into your inquiry email or project brief. Mark undecided items as “to be reviewed” and attach the files you already have.

• Project and contact: Company, contact person and reply email; part name and application.
• Drawings and revision: Part number, revision and units; attach the 2D drawing and any available 3D model.
• Sample or photos: State whether a sample is available; include overall, internal and interface views.
• Purchase plan: First-order quantity, expected batch quantity, reorder frequency and repeat demand.
• Material: Specified alloy grade and standard; whether alternatives may be evaluated.
• Critical interfaces: Mounting faces, mating bores, sealing locations and mating-part information.
• Holes and threads: Hole diameter, depth and direction; thread size and usable thread depth.
• Finish and appearance: Finishing process, color, texture, visible surfaces and reference samples.
• Coating and masking: Uncoated areas and boundaries; the finishing stage to which critical dimensions apply.
• Inspection and samples: Critical dimensions, appearance criteria, reports and sample approval requirements.
• Delivery plan: Raw or finished parts; target timing, packing and delivery destination.
• Open items and permitted changes: Questions for review and the permitted scope of design or process changes.

You do not need to complete every item before making contact. Start with the available information, then fill the gaps around the specific project.

How HSX Reviews and Develops a Project

HSX mainly supports small and medium-sized custom aluminum die casting projects based on customer drawings. The initial review covers part dimensions and geometry, wall thickness and casting feasibility, material, finish, quantities, tolerances and assembly requirements. These inputs help define a suitable manufacturing route and quotation basis.

HSX is responsible for mold design. Some mold manufacturing operations are completed in-house, with the remaining work arranged according to the agreed project scope. In-house operations include aluminum die casting, trimming, gate removal, deburring, drilling, tapping, polishing, powder coating, spray painting, quality inspection and packing. Each part uses the operations it requires. CNC machining, anodizing and electroplating are supported through partners, with their scope and suitability confirmed separately.

If the part does not fit the available equipment or process, the material is unsuitable, special machining remains unresolved, or tooling investment is disproportionate to the demand, feasibility and alternative routes should be discussed first. Project acceptance depends on the actual drawing, application and requirements.

Explore the relevant custom part direction for your project:

• Custom motor housings : Prepare mounting interfaces, critical hole locations and relevant fit requirements.
• Custom equipment and controller enclosures : Prepare assembly relationships, openings, appearance requirements and service conditions.
• Custom industrial brackets : Prepare hole positions, threads, connection details and loading conditions.
• Custom light and heat-dissipation housings : Prepare the housing geometry, mounting faces and surface requirements. The scope covers housings and structural parts.

Send your available drawing, 3D file, sample information or project brief to HSX. Include both confirmed requirements and open questions so the review can focus on your actual project.

Send Your Drawing for Project Review

Further reading: See how HSX takes a project from requirements review through manufacturing and delivery.