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Injection mold design and manufacture

Tooling starts with the details of your product. Share the part function, material, drawings and target injection machine to discuss mold design, manufacturing scope and sample-review requirements.

  • Part and resin
  • Machine and production
  • Sample and acceptance
Open injection mold with a red plastic enclosure

Part, material and machine. One connected decision.

SPHERE designs and manufactures plastic injection molds. Define the part function, geometry and material, then discuss cavity filling, cooling, part release and machine requirements. A drawing describes the shape; use, assembly and appearance requirements establish what to review in the design and sample.

Start with these questions

  • What does the part do, and which dimensions and surfaces matter?
  • Which material and grade, and what production volume is needed?
  • Which machine will run the mold, and how will the sample be reviewed?
The full RFQ checklist
Injection-mold core detail and part of the red enclosure

Tooling decisions take shape in the part.

Cavity count alone does not describe a mold. Review resin flow, part release, cooling and appearance together with machine data and the requirements of the finished part.

Topics for technical discussion. Selections and specifications are defined for your project scope.

Cavity count and layout

Review demand alongside part geometry, resin, machine limits and tool size. Cavity count belongs to the complete tooling decision.

Establish volume and machine data before fixing the cavity count.

Gates and runners

Discuss resin entry, flow path and the gate mark on the part. Review cold or hot runners against resin, geometry, maintenance and cost scope.

Identify surfaces where a gate mark would be unacceptable.

Parting line and ejection

Review opening direction, draft, ejector locations and features that restrict release. Side holes or undercuts may need additional tooling or a design revision.

Mark assembly areas and surfaces sensitive to ejector marks.

Cooling and operation

Review cooling layout, connections and available utilities with the tool geometry and resin. A product description alone cannot establish a cycle-time commitment.

Share the cooling-system information available at the production site.

Material and molded dimensions

Resin grade, walls, ribs and molding conditions inform dimensional and appearance review. Identify critical dimensions rather than applying one blanket tolerance.

Connect each critical dimension to its function and measurement method.

Inserts and replaceable details

Flag embedded product components or details that may change between revisions. Review inserts or replaceable tooling details against function, retention and maintenance access.

Distinguish components embedded in the product from inserts in the tool.

Surfaces, lettering and finish

Identify visible surfaces, texture, lettering or logos, and acceptable parting-line locations. Agree an appearance reference before using it as a sample-acceptance criterion.

Use an annotated drawing or reference sample to communicate appearance.

Components, maintenance and handover

Discuss components, wear items, connection information and operation/maintenance needs in the quotation. Define the included components and documentation in the quotation.

Clarify included items and accompanying documentation.

From a product brief to sample review.

Use these stages to discuss design, manufacture and supply scope. Work, trial, acceptance and timing arrangements belong in the project agreement.

  1. Define the part brief

    Gather drawings, resin, function, critical dimensions and machine data. Separate confirmed information from questions that still need answers.

  2. Review the tooling concept

    Discuss cavities, gating, cooling, parting, ejection and appearance. Identify proposed part revisions and decisions requiring approval before the design is fixed.

  3. Agree the quotation scope

    Clarify design, manufacture, components, trials and documentation, alongside acceptance criteria, responsibilities and project-specific agreed dates.

  4. Manufacture and sample trial

    Define trial arrangements, machine, resin and responsibilities in the agreement. Record the design revision, trial conditions and observations for review.

  5. Review acceptance and handover

    Compare samples with agreed criteria and resolve observations within scope, then establish the agreed handover, ownership, operation and care documentation.

Give sample review a clear reference.

Appearance, dimensions, function and trial conditions are different parts of the review. Define the checks, methods and responsibilities before accepting a sample.

Dimensions and measurement

Specify critical dimensions, drawing revision, required tolerances, measurement method and sample quantity. Review feasibility against resin and geometry.

Appearance and molding marks

Agree important surfaces, color/finish references, and acceptable locations for parting lines, gate marks and ejector marks.

Function and assembly

Identify mating parts, required fit or use checks, and who performs them. External appearance alone does not establish functional acceptance.

Trial conditions and observations

Record trial resin, machine, available settings, sample identification and drawing revision so observations have a clear reference.

Prepare an RFQ worth discussing.

Bring the information available and identify what is missing. You can start a conversation without a complete file; technical details and quotation scope need review before agreement.

Prepare an inquiry draft

Review the draft, then open WhatsApp and send it yourself. Share drawings in the conversation; this website does not upload files.

Product and function
Describe the use and mating parts, with a photo or sample if available. Identify load, fixing and assembly features, and details that must remain unchanged.
Drawing and revision
Provide available 3D data or a dimensioned drawing, revision, units and critical dimensions. Explain any differences between the drawing and an existing sample.
Material and grade
Identify polymer, grade, color and any additives or reinforcement, including virgin or recycled content if known. Share available material data rather than assuming its properties.
Appearance and finish
Mark visible surfaces, required texture or gloss, lettering and logo locations, and areas where gate or ejector marks are acceptable. A reference image or agreed sample helps describe the requirement.
Injection machine data
Share make, model and available nameplate/manual data: mounting space, mold height, opening and ejection strokes, and injection-unit information. Identify the machine before discussing compatibility.
Production and supply scope
State expected quantity, production frequency and any proposed cavity count. Clarify full design and manufacture versus manufacture to an existing design, and components or spares to include in the quotation.
Inserts and assembly
Identify metal, threaded or separate components with drawings, dimensions and intended assembly method. Explain whether they are introduced during molding or assembled afterward for technical review.
Trial, acceptance and handover
Define dimensions and functions to inspect, measurement method, trial resin and machine, and sample quantity to review. Agree trial responsibilities, documentation, ownership and handover within the quotation scope.

Before requesting injection tooling.

Answers to help prepare the information and identify decisions to discuss.

Which mold service does SPHERE provide?

Plastic injection mold design and manufacture. Each project is scoped around its part, resin, injection machine, production requirements and acceptance criteria.

Do I need a completed drawing to start?

You can start with a clear description and a photo or sample if available. Explain what you have and what is missing so drawing and information requirements can be discussed before scope is agreed.

How is cavity count determined?

Review production volume, part geometry, resin, injection-machine data and tool size together. Volume alone cannot establish a suitable count or machine compatibility.

Should I choose hot or cold runners?

Consider the part, resin, cavities, appearance, operation, maintenance and cost. Share current requirements and constraints so alternatives can be discussed for the proposed tooling scope.

Will the mold fit any injection machine?

Tool-machine compatibility needs available mounting, height, opening, ejection and injection-unit data. Share the model and machine reference at the start of the discussion.

What helps discuss price and timing?

Clear drawings, resin, machine data and production volume, plus cavity, runner, finish, trial and documentation requirements. Price and timing depend on the agreed scope of each project.

How should sample acceptance be defined?

Establish dimensions, functions, appearance, drawing reference, inspection method, trial resin and machine before review. Discuss tolerances, checks and responsibilities for the project; a photo cannot define them.

How do I share drawings and start an RFQ?

Prepare a mold-sector inquiry, review the WhatsApp draft and send it yourself. Describe available drawings and share them inside WhatsApp. This website does not upload files or send your request automatically.

Start with your part. Define the tooling need.

Your product, resin, available drawing and injection machine form a useful starting point for discussing mold design and manufacture.