Product Structure Design | Injection Product Structure Development & DFM

WHY SENRMOLD DESIGN

Why Entrust Structural Design to Senrui

We are not a pure design firm, but a structural team with our own molds and injection-molding lines—every rib and every snap-fit is drawn to standards that allow moldability, mass production, and assembly.

Mold-Molding Integration: Design That Knows the Mold

Structural and mold engineers review under one roof; parting surfaces, slide positions, ejection layout, and gate locations are confirmed before drafting, avoiding "can be drawn but not moldable."

DFM Risk Moved Upstream

Wall-thickness uniformity, draft angles, sink-mark and weld-line positions, ejection interference, and boss sink—each is cleared at the 3D stage, significantly reducing later mold and drawing revision costs.

CAE Dual Closed-Loop Verification

Structural schemes are simultaneously validated for moldability with Moldflow and for drop/strength with FEA; simulation results feed back into the structure, forming a 'design–simulation–improvement' closed loop.

Tolerance Chain & Assembly Reliability

Key fits are calculated segment by segment along the dimension chain; fit clearance, step, and flatness are annotated per GD&T, achieving assembly right the first time and reducing on-site fitting and selective assembly.

Material & Cost Alignment

The structural solution simultaneously gives material suggestions (ABS/PC/PC+ABS/PA+GF/TPE, etc.), weight estimation, and per-unit cost range, so the design lands within budget from the start.

Engineering Documents Delivered in One Package

3D models, 2D engineering drawings, exploded assembly drawings, BOM lists, DFM reports, and material & surface-treatment recommendations are delivered together in one package, ready for tooling or quotation.

CORE DESIGN CAPABILITY

Core Structural Design Capabilities

Complete structural development capability covering appearance, structural, connecting, and functional parts, adapted to consumer electronics, automotive interiors, medical, and smart home.

Appearance Part Structural Design

Class-A Surface Execution

Undertake industrial-design Class-A surfaces and CMF schemes; perform surface extension, parting-line design, step and fillet (R) treatment, balancing appearance quality with injection-molding feasibility.

Appearance fidelityClass A

Parting-Line DesignHigh-Gloss Spray-Free

CMF Implementation

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Internal Frame & Brackets

Spatial Integration

Positioning and fixation structure design for PCB/battery/motor/screen, including space stacking (stack-up), wiring channels, and thermal/ventilation layout.

Space UtilizationExcellent

Stack-upWire routing channel

Stack-up Evaluation

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Snap-Fit & Joint Structures

Screw-Free

Design of snap-fits, undercuts, hooks, studs, heat-stake posts, and ultrasonic welding lines; back-calculate cantilever thickness and undercut amount from insertion/retention forces.

Assembly ReliabilityHigh

Insertion/Extraction Force CalculationScrewless Assembly

Mechanical Verification

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Sealing & Waterproof Structures

IPX Rating

Silicone ring / foam / dispensing / two-shot overmolding sealing solutions; compression ratio and groove dimensions are back-designed per IP54–IP68 targets.

Protection ratingIP68

Groove DesignCompression Ratio Check

Seal Selection

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Inserts & Hard-Soft Integration

Fully Integrated

Pre-insert nuts / terminals / bushings; TPE / TPU two-shot overmolding soft-touch design, reducing post-assembly steps and connection failure risk.

Process IntegrationHigh

Insert EmbeddingTwo-Color Overmolding

Assembly Reduction

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Structural Optimization & Lightweighting

Cost Reduction & Efficiency Gain

While meeting strength and appearance requirements, reduce wall thickness, optimize ribs and material removal, lower part weight and molding cycle, directly compressing per-piece cost.

Weight / cost reduction8–20%

Wall Thickness OptimizationCycle Reduction

Cost Reduction

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DESIGN PROCESS

Structural Development Process

A ten-step standardized chain from product definition to mass-production support, with clear deliverables and review milestones at each step; progress and risk are traceable throughout.

Requirements & Specifications

PRD / Appearance Concept

Conceptual Structure Proposal

Stack-Up Layout

3D Structural Modeling

UG／SolidWorks

Part Splitting & Mold Separation

Parting Line Definition

DFM Review

Manufacturability Check

CAE Verification

Mold Flow + FEA

Prototype Verification

3D Printing / CNC

2D Engineering Drawings

GD&T Annotation

Mold Handoff

Tooling Data Freeze

Mass Production Support

Design Changes & Optimization

DELIVERABLES

Standard Deliverables List

One structural development delivers a full set of engineering documents ready for tooling, quoting, and quality control.

3D Structural CAD Model

Native formats (PRT/SLDPRT/CATPart) + common formats (STEP/IGES/X_T), including the complete feature tree, editable.

2D Engineering Drawings

Includes key dimensions, tolerances, datums, GD&T geometric tolerancing, surface treatment, and appearance grade requirements, in both PDF + DWG.

DFM Manufacturability Report

Wall-thickness cloud map, draft check, sink-mark risk points, weld-line location, parting and ejection scheme, risk level and improvement suggestions.

Exploded View & Assembly Instructions

Part hierarchy, assembly sequence, torque/insertion force requirements, and mistake-proofing design notes—facilitating production-line and customer reviews.

BOM (Bill of Materials)

Part number, material grade, color, surface treatment, supply method (in-house / outsourced), estimated weight and usage.

Tolerance Chain Analysis Sheet

Step-by-step calculation of critical fit dimension chains, including worst-case and statistical results, outputting assembly clearance and step-gap predictions.

Material & Process Recommendations

Resin selection comparison (mechanical / weather resistance / flame retardancy / odor), mold steel recommendations, and surface treatment (spraying / plating / texturing / high-gloss) solutions.

Mass Production Cost Estimate

Combining part weight, cycle time, cavity count and machine tonnage to provide per-unit cost ranges and rough mold cost, facilitating project decisions.

SOFTWARE & STANDARD

Design Software & Technical Standards

Fully compatible with mainstream CAD / CAE platforms; accepts customer data in any format and produces drawings per customer corporate or industry standards.

UG NX

Primary 3D Platform

Parametric Modeling / Surfacing

SolidWorks

Structure & Sheet Metal

Assembly & Engineering Drawings

CATIA

Class-A Surfacing

Automotive Interior & Exterior Trim

Creo

Parametric Design

Family Tables & Configurations

Moldflow

Moldability Verification

Fill / Warpage

Abaqus／Ansys

Structural Verification

Drop / Strength

Specification Item	Senrui Design Standard	Notes
Wall Thickness Design	General parts 1.5–2.5 mm, with uniform transition.	Keep wall-thickness difference within ±20% to avoid sink and warpage; transition thick-to-thin at a 3:1 gradient.
Draft Angle	Appearance face ≥1°; textured face ≥1.5°–3°.	Increase draft with depth for deep cavities and long ribs to prevent scuffing and ejection deformation.
Ribs	Rib thickness ≤ 60% of main wall; height ≤ 3× wall thickness.	Add R at the root to avoid sharp-corner stress concentration and surface sink marks.
R Radius	Inner R ≥ 0.5 mm, outer R = inner R + wall thickness	Eliminate stress concentration; improve melt flow and ejection.
Screw Boss / BOSS	OD ≈ 2× bore; wall thickness ≤ 60% of main wall.	Add sink-proof design at back (coring / cross ribs); add R at bottom.
Hole Position & Edge Distance	Hole edge distance ≥ bore; hole-to-edge ≥ 1× wall thickness.	Avoid weld lines on load-bearing and appearance areas
Snap-Fit Design	Undercut 0.5–1.2 mm; cantilever length/thickness ratio 5–10	Back-calculate from PC/ABS allowable strain to ensure no fracture after repeated mating.
Tolerance Annotation	GB/T 14486 MT class, or customer's enterprise standard.	Assign tolerances individually to key dimensions; general dims per class uniformly.

CASE STUDIES

Structural Design Case Studies

Below are representative structure-development project types (examples, not specific customers), demonstrating cross-industry structure design capability.

Consumer Electronics Example

Smart Terminal Full-Device Structure

Four-piece structure of top/bottom shells + mid-frame + screen bracket; hybrid snap-fit + screw assembly; passes 1.5 m drop; wall thickness 1.8 mm, overall weight reduced 12%.

Snap-Fit AssemblyDrop PassLightweighting

Automotive Interior Example

Automotive Trim & Air Vents

PC+ABS paint-free high-gloss trim + TPE soft-touch overmolding; materials are selected per VOC and weather-resistance requirements, and steps and mating surfaces are controlled within 0.3 mm via tolerance chains.

Two-Shot OvermoldingSpray-FreeDimension Chain

Medical Device Example

Handheld Medical Device Housing

S136 mold steel paired with medical-grade PC, IP65 sealed structure (silicone ring compression rate 20%), resistant to alcohol wiping and high-frequency disinfection.

IP65Medical MaterialSealed Structure

Smart Home Example

Small Appliance Functional Structural Parts

PA+GF frame + ABS housing, integrating motor vibration damping, water-channel sealing, and cooling air ducts; assembly part count reduced from 14 to 9.

Vibration Damping DesignPart SimplificationCooling Air Duct

0

Cumulative Structural Development Projects

0

Manufacturing Experience

0

DFM First-Pass Rate

0

First Proposal Delivery

CORE METRICS

Core Metrics · Quantified Capability

The value of structural design ultimately shows in first-time mold success, first-time assembly, and mass-production yield. Typical project statistics are below.

95%

DFM First-Review Pass Rate

Zero Risk Before Tooling

92%

First Structure Ready for Tooling

No Major Structural Rework Required

88%

First-Pass Prototype Assembly

Upfront Tolerance Chain Calculation

90%

Critical Dimensions Meet Drawing

First-Article CMM Verification

85%

Customer Requirements Frozen at Once

Upfront Requirement Review

95%

Design Lead Time Achievement Rate

92%

Tooling Data Frozen at Once

88%

Repeat Customer Rate

Note: the above are typical project statistical ranges; actual results vary with product complexity, appearance grade, and frequency of customer-change requests; formal projects follow the reviewed and confirmed delivery checklist.

SERVICE MODE

Service Model Comparison

From single-point support to design + tooling + mass-production full package, flexibly matched to your project stage and internal resources. Click tags to view details.

Full structural design (from 0 to mold-ready)

The client provides the product definition and appearance scheme (or only a requirements description); we complete all work from conceptual structure to tooling-ready data and deliver the full set of engineering documents.

Applications

New product developed from scratch, client has no structural team, appearance set but lacks engineering execution.

Deliverables

3D models + 2D drawings + DFM report + BOM + assembly drawings + material and cost recommendations.

Typical Cycle

Simple parts 7–10 working days; complete machines 15–30 working days (depending on part count and appearance grade).

Structural optimization and improvement (existing digital model)

The customer already has a 3D model but it suffers from molding defects, assembly difficulty, insufficient strength, or high cost. We provide targeted optimization and deliver an improvement report.

Applications

Recurring trial defects, low mass-production yield, unit cost to be reduced, customer demands weight reduction.

Common Optimizations

Wall-thickness equalization, rib relocation, gate position adjustment, boss anti-sink, clip mechanics recalculation, material removal for weight reduction.

Deliverables

Optimized model + before/after comparison report (defects / gram weight / cycle / cost).

Standalone DFM Review Service

Review only, no structural changes: before the customer's digital model goes to tooling, we issue an independent third-party perspective DFM review report that clarifies risks upfront.

Applications

The customer has its own structure team and needs a manufacturing-side review; or wants unified specs before quoting across multiple mold shops.

Review Dimensions

Wall thickness / draft / shrinkage / weld line / demolding interference / parting feasibility / cavity count and machine matching.

Typical Cycle

Report in 2–5 working days, including risk level and improvement priority ranking.

Structural Design + Tooling + Mass Production Package

From structural design all the way to mold and injection molding mass production, with single accountability and minimal interfaces; design changes and mold-trial issues are resolved internally in a closed loop.

Comparison Dimensions	Structural design + turnkey molding (Senrui)	Design & Tooling Outsourced Separately
Responsibility Boundary	Single Point of Accountability	Design and Mold Maker Blame Each Other
Mold / Drawing Change Response	Internal Kickoff Same Day	Cross-company communication, long cycle
DFM Depth	Parting line and ejection confirmed before drafting	Problems found only at mold stage
Mold Trial Issue Diagnosis	Design / Mold / Process Joint Review at Same Plant	Hard to Define Responsible Party
Total Cost	Reduce mold revision and rework losses	Low per-item quote but high hidden costs
Project Cycle	Design and Material Prep in Parallel, Overall Shorter	Serial waiting, stacked cycles

On-Site / Remote Engineering Support

Provide structural engineering resources on a man-month or project basis, participating in customer internal reviews, following up on molds and mold trials, as an extension of the customer's engineering team.

Applications

Client's peak project period lacks manpower; needs manufacturing-end engineers to follow the project long-term.

Working Method

Remote weekly meetings + data collaboration, or on-site as needed; supports customer enterprise standards and customer PLM workflows.

Billing Method

By man-month or by milestone; start after both parties sign an NDA.

DESIGN PITFALL & FIX

Common Structural Defects & Design Countermeasures

The roots of many mass-production problems are planted at the drawing stage. The table below lists the most frequent pitfalls in structural design and our standard practice.

FAQ	Root Cause at Structural Level	Design Countermeasure	Mass Production Support Measures
Sink Marks on Appearance Surfaces	Bosses and ribs too thick, back-side wall thickness buildup	Reduce rib thickness to 50–60% of main wall; hollow the stud back or switch to cross ribs.	Extend hold, optimize gate location and hold curve.
Product Warpage & Deformation	Uneven wall, one-sided ribs, uneven ejection stress.	Uniform wall thickness, symmetric ribs, add anti-warp ribs.	Balance cooling channels; adjust ejection and cooling time.
Snap-Fit Fracture / Assembly Failure	Cantilever too short/thick, undercut too large, no R at root.	Back-calculate length-to-thickness ratio 5–10 from allowable material strain; add R≥0.3 mm at the root.	Keep weld lines off the clip root; verify insertion/extraction force.
Sharp Corner Cracking	Inner R of 0 causes stress concentration	Add R≥0.5 mm to all internal corners; increase to 1 mm+ in load-bearing zones.	Drop/strength simulation review of max principal strain
Demolding Drag / Ejector Whitening	Insufficient draft angle, high deep-cavity clamping force	Appearance surface ≥1°, textured surface ≥1.5°, deepen to 2–3° for deep cavities.	Mirror polish + nitriding to cut friction; enlarge ejector-pin area.
Assembly Step / Uneven Gaps	No dimensional chain calculation; tolerances marked arbitrarily	Worst-case tolerance stack-up for key fits; allocate the tolerance budget.	First-article CMM verification, mold-side fit-grinding correction
Weld Lines in Load-Bearing / Appearance Areas	Gate Location & Hole Layout Not Coordinated	Adjust hole/rib position, or revise the gate plan with the mold side.	Moldflow verifies weld-line location and gas marks.
Seal Failure / Water Leakage	Groove size and compression rate mismatch; press-point spacing too large.	Design grooves to the IP target, compression 15–25%, sealing-point spacing ≤30mm	Seal selection verification + full-unit air/water tightness test.

On Confidentiality & Intellectual Property

A Non-Disclosure Agreement (NDA) can be signed before any structural development project begins. Product definitions, appearance concepts, and technical materials provided by the customer are used solely for the project; the intellectual property of any new structural 3D models, engineering drawings, and design documents we develop for the customer belongs to the customer as stipulated in the contract. Project data is stored in isolated partitions and accessed by project-based authorization, and upon project completion is returned or destroyed per the customer's request.

FAQ

Questions you may have about structural design cooperation.

I only have appearance drawings or an idea, no 3D data — can you do it? +

Yes. This is the most common starting point. We first confirm requirements and specifications (dimensional envelope, internal component list, assembly method, cosmetic grade, target cost and certification requirements), then produce a conceptual structure proposal and stack-up layout; after customer approval we move into detailed modeling. If even the appearance design is not yet defined, we can also start with a structural feasibility proposal based on functional requirements.

How are structure design lead time and cost calculated?+

The cycle is directly tied to part count, appearance grade, and functional complexity: a single simple structural part typically yields a first draft in 7–10 business days, and a full-unit project in 15–30 business days. Fees are assessed by part count and engineering effort; if tooling and mass production follow at Senrui, the design fee can be offset by an agreed ratio. The formal quotation prevails.

Which software formats do you support? Will there be any data conversion loss?+

The main 3D platforms are UG NX and SolidWorks, and we can also handle CATIA, Creo, and Inventor data; generic formats supported include STEP/IGES/X_T/STL/Parasolid. We prioritize the customer’s native format to preserve the feature tree and avoid losing parametric editability after conversion; if only intermediate formats can be provided, we rebuild editable features.

Can we participate in the review during the design process?+

Yes, and we strongly recommend it. The standard process includes three formal review gates: concept design review, 3D structure review (including DFM), and pre-drawing freeze review. At each gate we provide annotated 3D views or lightweight models (viewable in a browser); the next stage begins only after customer confirmation, avoiding directional rework.

Does structure design include concurrent simulation verification?+

Yes. Before finalizing the structural design, we use Moldflow to verify moldability (filling, weld lines, warpage) and FEA to verify mechanical performance (drop, small-ball impact, press strength). The two types of simulation results feed back into structural improvement, forming a closed loop. Simulation services can also be commissioned separately; see the 'FEA Structural Simulation' page for details.

After design is complete, must the mold be made at Senrui?+

Not mandatory. Structural design can be delivered as a standalone service; after receiving the full data set, customers may choose their own mold maker. Of course, if mold making and mass production are done together at Senrui, the design–mold–trial communication chain is shortest, with the fastest response to mold changes and design revisions, and typically lower hidden costs.

Turn your product idea into mold-ready drawings.

Whether you have only an appearance drawing, a competitor sample, or an old model that needs optimization, we can provide an implementable structural solution. Send your requirements to get a free preliminary assessment and structural feasibility judgment.

Submit Structure Requirements Estimate Injection Molding Cost Online

Product Structure Designfor injection-mass-production manufacturability development

Why Entrust Structural Design to Senrui

Mold-Molding Integration: Design That Knows the Mold

DFM Risk Moved Upstream

CAE Dual Closed-Loop Verification

Tolerance Chain & Assembly Reliability

Material & Cost Alignment

Engineering Documents Delivered in One Package

Core Structural Design Capabilities

Appearance Part Structural Design

Internal Frame & Brackets

Snap-Fit & Joint Structures

Sealing & Waterproof Structures

Inserts & Hard-Soft Integration

Structural Optimization & Lightweighting

Structural Development Process

Requirements & Specifications

Conceptual Structure Proposal

3D Structural Modeling

Part Splitting & Mold Separation

DFM Review

CAE Verification

Prototype Verification

2D Engineering Drawings

Mold Handoff

Mass Production Support

Standard Deliverables List

3D Structural CAD Model

2D Engineering Drawings

DFM Manufacturability Report

Exploded View & Assembly Instructions

BOM (Bill of Materials)

Tolerance Chain Analysis Sheet

Material & Process Recommendations

Mass Production Cost Estimate

Design Software & Technical Standards

Structural Design Case Studies

Smart Terminal Full-Device Structure

Automotive Trim & Air Vents

Handheld Medical Device Housing

Small Appliance Functional Structural Parts

Core Metrics · Quantified Capability

Service Model Comparison

Full structural design (from 0 to mold-ready)

Applications

Deliverables

Typical Cycle

Structural optimization and improvement (existing digital model)

Applications

Common Optimizations

Deliverables

Standalone DFM Review Service

Applications

Review Dimensions

Typical Cycle

Structural Design + Tooling + Mass Production Package

On-Site / Remote Engineering Support

Applications

Working Method

Billing Method

Common Structural Defects & Design Countermeasures

On Confidentiality & Intellectual Property

FAQ

Turn your product idea into mold-ready drawings.

Processes & Services

Quick Links

Contact Information

Product Structure Design
for injection-mass-production manufacturability development