Product definition & specification
Defining product intent, engineering constraints, risk questions, and the specification sheet that suppliers quote against. Includes a fillable XLSX spec sheet template.
Resources / R-04 — Hardware reference library
Hardware reference documents.
Twenty-three reference documents covering the hardware product lifecycle — definition, design, electronics, sourcing, production, compliance, logistics, and launch. Three include fillable Excel templates. Written and maintained by Ideambox engineering.
§ A — Definition & strategy
Define the product
Industrial design brief
The pre-engineering deliverable that sets form language, ergonomics, materials, finishes, and brand alignment. Bridges marketing intent and mechanical CAD.
Cost engineering & VA/VE
Target costing, BoM cost analysis, Value Analysis / Value Engineering methodology, design-for-cost rules, and real cost-reduction examples from consumer hardware.
§ B — Mechanical & materials
Mechanical design
Design for manufacturing
Mechanical DFM (injection molding, sheet metal, CNC), electronics DFM (PCB layout, panelisation, design for test), and assembly DFM. Bridges design intent and production reality.
GD&T reference
Geometric Dimensioning & Tolerancing (ASME Y14.5 / ISO 1101) — symbols, modifiers, datum reference frames, and verification methods for precision parts.
O-ring selection guide
Elastomer choice (NBR, FKM, EPDM, silicone, FFKM), hardness, AS568 / ISO 3601 sizing, and gland design — squeeze, fill, extrusion and back-up rings — with failure modes and a selection checklist.
Bolted joint reference
Preload-first fastener design: property classes (8.8 / 10.9 / 12.9), torque-to-tension and the nut factor, thread engagement, locking methods, and fastener failure modes.
Engineering materials datasheet
Typical mechanical properties of common metals and engineering plastics — density, modulus, yield, UTS, CTE and service temperature — with selection trade-offs and quick guidance.
Surface finish reference
What Ra/Rz mean, typical roughness by process, the finish each function needs (sealing, bearings, fatigue, fits), ISO 1302 drawing call-outs, and a conversion / N-grade table.
Bearing selection guide
Rolling vs plain bearings, the L10 life calculation and load rating, mounting fits and the locating/floating arrangement, lubrication, the PV limit for bushings, and bearing failure modes.
Fatigue design primer
High-cycle fatigue design: the S-N curve and endurance limit, the Marin modifiers (surface, size, load, reliability), mean-stress correction (Goodman / Gerber / Soderberg), and stress concentration / notch sensitivity.
Shaft-hub connections
Transmitting torque shaft-to-hub: interference (press/shrink) fits and their torque, keys and keyways with standard sizes, splines, tapers, clamp hubs and keyless bushings — with a selection guide.
Gasket selection guide
Static-seal selection: gasket types and materials (fibre, PTFE, graphite, spiral-wound, metal, liquid), seating stress and bolt load (m/y factors), flange design, and leak failure modes.
Hardness conversion reference
The hardness scales (Brinell, Rockwell, Vickers, Shore), an approximate steel conversion table between HV/HBW/HRC/HRB and tensile strength, and how to pick the right test.
Lubrication and grease guide
Choosing oil or grease: lubrication regimes (Stribeck), ISO VG oil grades, grease NLGI and thickener types, AW/EP and special additives, and compatibility with seals and plastics.
Unit conversion reference
Everyday SI ↔ imperial engineering conversions: length, mass and force, pressure/stress, torque, energy, power, temperature, viscosity and rotation, plus SI prefixes.
Gear design basics
Gear types (spur, helical, bevel, worm), the module and pitch geometry, ratio and torque, tooth strength (bending + pitting), quality / backlash / lubrication, and failure modes.
Hertz contact stress
Contact stress between curved bodies: point and line contact formulas, effective modulus E* and radius R*, the subsurface shear that drives pitting, and allowable contact-stress limits.
Welded and adhesive joints
Permanent joining: fusion welds (joint types, ISO 2553 symbols, throat sizing), brazing and soldering, and adhesive bonding (families, design for shear, surface prep) with failure modes.
Sheet-metal design guide
Bent sheet-metal design: bend allowance and the K-factor, minimum bend radii and reliefs, hole/edge rules, forming features, and DFM — with a live Excel bend calculator.
Snap-fit and living-hinge design
Plastic snap-fits (cantilever, annular, torsional) — strain limits, retention vs assembly force — and integral living hinges (geometry, PP/PE, fatigue), with failure modes.
Heat and surface treatment
Steel heat treatment (anneal, normalize, quench & temper, stress relief), surface hardening (carburize, nitride, induction), and plating/coatings — anodize, passivation, EN, chrome, PVD — with gotchas.
Galvanic and corrosion compatibility
Which metals can touch: the galvanic series and anodic-index rules, area-ratio effects, the other corrosion forms (pitting, crevice, SCC), and mitigation by isolation and selection.
Tap-drill and thread chart
Tap-drill and clearance-hole sizes for metric (M1.6–M20 coarse) and inch UNC threads, with the tap-drill ≈ major − pitch rule. Fillable Excel lookup.
Wear and material-pairing guide
Designing against wear: the wear mechanisms (adhesive, abrasive, fatigue, fretting), friction and which material pairs to run together, the PV limit, and wear-resistant materials and coatings.
Retaining rings and pins
Thread-free retention and location: retaining rings/circlips (external/internal, E-clip, spiral) for axial thrust, and dowel/spring/clevis pins for location and shear, with groove and hole design.
Resistor and capacitor values and codes
Passives reference: the E-series preferred values, 4/5-band resistor colour and SMD codes, capacitor codes and dielectric types (C0G/X7R/X5R), and power/voltage derating.
PCB stack-up and impedance
PCB layer stack-ups (2/4/6-layer), controlled impedance (microstrip vs stripline, 50/90/100 Ω targets), return paths and power integrity, and what to specify to the fab.
Battery and power-budget worksheet
Fillable power-budget calculator: enter loads (active current × duty cycle) and battery parameters to get average current, estimated runtime, and the capacity needed for a target life.
Connector selection guide
Choosing connectors: the families (JST, Molex, headers, terminal blocks, FFC, power, RF), per-contact current and pin-count/temperature derating, plating (gold vs tin), and mating cycles.
ESD and EMC design checklist
Designing for EMC and ESD: grounding and return paths, filtering and decoupling, layout for low emissions/high immunity, and I/O protection (TVS) — before the test lab.
Tolerance stack-up worksheet
Fillable worst-case and RSS tolerance stack-up: one row per contributor (nominal, ±tol, direction) auto-computes the nominal gap and the worst-case and statistical min/max.
DFMEA / risk register template
Fillable design-FMEA: one row per failure mode with Severity, Occurrence, Detection; live RPN = S×O×D, a high-risk count, and the rating scale. Prioritise the highest RPN.
DVP&R test matrix template
Fillable Design Verification Plan & Report: requirement → method, acceptance, sample, phase (EVT/DVT/PVT) and Pass/Fail result, with live pass/fail/open counts and pass rate.
Should-cost model
Bottom-up cost build-up for a manufactured part or assembly: material, conversion (machine + labor + setup), tooling amortization, overhead, SG&A and margin to ex-works and landed cost — with a live where-every-euro-goes breakdown and a should-cost vs supplier-quote delta.
Engineering change (ECR/ECN) management
Controlling change after release: the ECR→review→ECN→effectivity flow, change classification (major/minor, interchangeability), disposition of existing stock, and revision/BoM impact — with a fillable Excel ECR/ECN log and notice form.
Sustainable materials reference
Brand materials, certified materials, generic natural and recycled materials — sourcing, certification costs, and the substantiation rules under US FTC Green Guides and EU Green Claims Directive.
§ C — Electronics & firmware
Electronics design
Electronics & PCB design
Schematic best practices, layer stack-up selection, decoupling strategy, signal integrity, grounding for EMC, and the DFM/DRC rules that determine first-pass yield.
Battery & power management
Li-ion chemistry selection, BMS architecture, charging design, fuel gauging, and the safety standards (UN 38.3, IEC 62133, EU Battery Regulation) that govern shipping and sale.
EMC design & pre-compliance
Applicable standards (EN 55032, FCC Part 15), grounding and shielding rules, filtering and decoupling, ESD protection, the pre-compliance workflow, and common failure modes.
Wireless & antenna integration
BLE / Wi-Fi / LTE / LoRa selection, pre-certified modules vs. custom RF, antenna topology and tuning, and the regulatory paths (RED, FCC Part 15C, IC).
Firmware architecture & MTM
Embedded firmware patterns (HAL, RTOS, bare-metal), Manufacturing Test Mode (MTM) for production lines, OTA update architecture, and security baseline (EU CRA, UK PSTI).
§ D — Prototype & test
Validate the build
Prototype test plan template
Structure for committing prototype-round questions, test methods, and decision criteria to writing before the prototype is built. Includes standard environmental test references (IEC 60068, MIL-STD-810).
§ E — Sourcing & supplier
Source & quote
Supplier RFQ checklist
RFQ package contents, supplier qualification questions, red-flag detection, tooling cost benchmarks, and the contract clauses that prevent later disputes. Includes a fillable XLSX quote-comparison template.
BOM & component sourcing
BoM structure, component lifecycle (NPI/Active/NRND/EoL), second-source planning, lead-time and MOQ management, counterfeit risk. Includes a fillable XLSX BoM template.
Sourcing beyond China
Vietnam, India, Thailand, Taiwan as alternatives or complements to mainland China — capabilities by country, real cost benchmarks, Section 301 tariff impact, supplier-discovery channels.
§ F — Production & quality
Run production
Quality control & inspection
AQL sampling (ISO 2859), defect classification, Cp/Cpk with worked examples, inspection types (IQC/IPQC/FQC/PSI), and process-specific defect catalogues.
Production ramp-up plan
Pilot-to-MP gate criteria, yield ramp targets, operator training and line balancing, capacity planning, and risk management during the first 8-12 weeks of mass production.
Product safety & certification
US and EU compliance reference — applicable directives, lab cost benchmarks, the technical-file structure, pre-compliance workflow, and common failure modes with fix costs.
§ G — Logistics, launch & post-launch
Ship, protect & support
Importing from Asia
Five-part operational reference: product specifications, supplier sourcing, product samples, agreement and QA, shipping and customs. The end-to-end import workflow with Letter of Credit structure.
Shipping, taxes & customs
Incoterms 2020, sea vs. air freight, customs-value calculation (US FOB vs. EU CIF), HS codes for electronics, FTA preferences (USMCA, RCEP, EU-Vietnam), worked customs calculations.
IP protection for hardware
Trademarks, design rights, utility patents, trade secrets — with detailed cost and timeline tables, Madrid Protocol, patent search tools, NDA template, freedom-to-operate analysis.
Crowdfunding to production
Platform selection (Kickstarter vs. Indiegogo), pre-launch engineering readiness, marketing budget benchmarks, post-funding production timeline, and the fulfilment economics that determine margin.
Warranty & field service
Warranty policy design (EU 2019/771, US Magnuson-Moss), RMA process, field-failure analysis, MTBF estimation, support tiers, and the cost reserves required to make post-launch service sustainable.
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