Special Purpose Machines

Transfer Machines · PLC Automation · Cam Mechanisms · Jig & Fixture · Poka-Yoke

Neo Materials designs and builds Special Purpose Machines (SPM) and multi-station transfer lines for high-volume production. Every machine is engineered from first principles — cam profiles, hydraulic circuits, PLC ladder logic, and safety systems — then validated through Cycle Time Analysis and OEE simulation before delivery.

<8 s

Cycle Time

S7-1500

PLC Platform

PLe Cat.4

Safety Rating

>85% OEE

Guaranteed

Request SPM Design Explore Capabilities ↓

SPM ENGINEERING LABORATORY

Special Purpose Machines: 10-Module Technical Tour

Architecture, cam mechanisms, pneumatics, hydraulics, PLC, fixtures, poka-yoke, quality integration, and deliverables.

SPM Machine Architecture

A Special Purpose Machine is engineered for a single product family, maximising output rate by integrating all operations (drilling, reaming, tapping, pressing, gauging) into a single automated transfer line. Architecture is determined by production rate, part weight, operation sequence, and poka-yoke requirements.

Machine typesIn-line transfer, rotary index, dial

Station count4–16 stations (application-dependent)

Indexing mechanismGeneva, cam, servo-driven

Transfer typeContinuous, intermittent, free-flow

Cycle time target<8 s/part (typical)

Machine frameRibbed cast iron / welded steel

Rotary dial machines are preferred for small, symmetric parts (under 2 kg) with ≤8 operations. In-line transfer is used for heavier parts or when operations require large forces (pressing, broaching) that would cause vibration cross-contamination in a dial machine.

Cam Mechanism Design

Plate and cylindrical cams convert rotary shaft motion into precisely timed linear/rotary follower displacement. Cam profile is designed using displacement, velocity, and acceleration (DVA) diagrams to achieve smooth motion (RDFD — Rise-Dwell-Fall-Dwell). Jerk minimisation prevents follower bounce and vibration.

Cam profileCycloidal / modified trapezoidal

Rise angle60–90° (RDFD cycle)

Follower typeRoller (anti-friction), flat-face

Cam materialEN31 / D2 steel HRC 58–62

Pressure angle≤ 30° (translating follower)

Contact stressHertz: σ_H = E*√(F_n/ρ_eq)

Pneumatic System Design

Pneumatic circuits provide fast, clean actuation for clamping, ejecting, and tool advance. Every SPM pneumatic system is designed per ISO 1219 with FRL units, double-acting cylinders, 5/2 solenoid valves, flow controls, and manifold blocks. System pressure: 6 bar nominal.

Working pressure6 bar (0.6 MPa)

Cylinder boreØ25–Ø160 mm (SMC, Festo)

Valve type5/2 solenoid (24V DC)

Response time20–40 ms (SMC VQ)

FRL filter5 µm element, auto-drain

Cylinder forceF = P × A × η (η = 0.85)

Hydraulic System Design

High-force operations (pressing, broaching, forging inserts) require hydraulic actuation at 100–350 bar. Hydraulic Power Unit (HPU) design covers pump sizing, accumulator sizing, directional control valve selection, and system thermal analysis. Contamination control: NAS 1638 Class 7 filtration.

System pressure100–350 bar

Pump typeVariable-displacement piston

Filtration10 µm β₁₀≥200 (NAS 7)

Oil temp range35–55°C (oil cooler)

Valve typeProportional / servo valves

Force capabilityUp to 2,000 kN (200T press)

HPU SIZING CALCULATION

Required force: F = 500 kN
System pressure: P = 250 bar
Cylinder bore: A = F/P = 500,000/25 = 20,000 mm²
→ Bore = Ø160mm (A = 20,106 mm²)
Pump flow: Q = A × v_cyl = 20,106 × 0.05
= 1,005 cm³/s = 60.3 L/min
Motor power: Pm = P × Q / η = 25 kW

PLC Ladder Logic & HMI

Siemens TIA Portal (S7-1500) or Allen-Bradley Studio 5000 (ControlLogix) PLC programming for full SPM machine sequencing, fault handling, and production counting. HMI (Siemens KTP900 or Weintek) provides operator interface with production status, alarm management, and recipe changeover.

PLC platformSiemens S7-1500 / AB CLX

I/O count (typical)64–256 DI/DO + 16 AI/AO

Scan cycle1–5 ms

Safety PLCS7-1500F (Fail-safe)

HMISiemens KTP900 / Weintek cMT

CommunicationPROFINET / OPC-UA

// LADDER LOGIC — STATION 2 DRILL CYCLE
|--[Part_Present]--[Clamp_OK]--------( Start_Drill )--|
|                                                      |
|--[Start_Drill]--[TON T2 PT:3s]---( Drill_Down )--|
|                                                      |
|--[T2.DN]------------------------( Drill_Up )---------|
|                                                      |
|--[Drill_Up_LS]--[NOT Fault]-----( Station_Done )--|
|                                                      |
|--[Fault_Any]--------------------( E_Stop_All )-------|

Jig & Fixture Design — 3-2-1 Principle

Fixtures locate parts using the 3-2-1 principle (6 degrees of freedom removal): 3 locators on primary plane, 2 on secondary plane, 1 on tertiary plane. Diamond pins for repeat location. Toggle clamps for fast loading. CMM-verified fixture accuracy ≤0.010 mm.

Locating principle3-2-1 (6 DOF removal)

Primary locators3 × flat contact pads (Z-axis)

Secondary locators2 × V-block or flat (X-axis)

Tertiary locator1 × stop pin (Y-axis)

Diamond pinAllows thermal expansion (1 DOF)

Fixture accuracy≤ 0.010 mm CMM verified

Poka-Yoke Error-Proofing Systems

Poka-yoke (mistake-proofing) devices prevent defects by making wrong actions impossible or immediately detectable. SPM machines integrate physical error-proofing geometry and sensor-based detection at every station, targeting zero-defect production without reliance on operator vigilance.

📐 Shape Geometry

Fixture nest geometry allows only correctly oriented parts to seat. Wrong-side-up or mirror-image parts are physically rejected by asymmetric locating pin positions — no operator intervention needed.

👁 Part-Present Sensors

Inductive / fiber-optic sensors at each station confirm part presence before cycle starts. Machine won't index or activate spindles if part is missing, preventing tool crashes and empty-cycle waste.

🔢 Count Verification

Spindle encoder monitors drill rotation count. If fewer than required revolutions (thread depth), the part is flagged as NG and rejected by pneumatic ejector before next index. Catches tap breakage instantly.

⚖ Torque Monitoring

Servo-driven tapping stations monitor torque signature vs. golden sample. Torque outside ±15% window → automatic reject and alarm. Detects hard spots, wrong material, and worn taps.

📏 In-Process Gauging

Air gauging at dedicated gauge station: bore diameter measured to ±0.001 mm every cycle. Results feed SPC chart. Parts outside tolerance auto-rejected. No post-process CMM needed for routine checking.

🔴 Colour Coding

Tool holders, fixtures, and consumables colour-coded by product variant. Wrong colour = wrong setup → operator immediately recognises mismatch. Eliminates part mix-up on multi-product lines.

Cycle Time Analysis & OEE

Cycle time analysis identifies the bottleneck station and defines achievable throughput. Every SPM is designed with a target OEE ≥ 85% and cycle time ≤ takt time. OEE is tracked live via SCADA and posted daily in A3 format per lean manufacturing practice.

Takt timeT_T = Net time / Demand

Cycle time target≤ Takt time (no over-production)

BottleneckStation with max operation time

OEE formulaA × P × Q

World-class OEE≥ 85%

Neo guarantee≥ 85% within 4 weeks

8-STATION SPM EXAMPLE

Demand = 10,000 pcs/day (480 min avail.)
Takt = 480×60/10000 = 2.88 s
Cycle time designed = 2.6 s
Availability = 93% (planned stops)
Performance = 97% (minor speed loss)
Quality = 99.5% (Cpk 1.67)
OEE = 0.93 × 0.97 × 0.995 = 89.8% ✔

In-Process Quality & SPC

In-line gauging feeds a real-time SPC database (InfinityQS / Q-DAS). X̄-R charts with all 9 Western Electric Rules trigger automatic machine stop on out-of-control condition. Cpk ≥ 1.67 is contractually guaranteed for all critical dimensions on Neo SPM machines.

Gauging methodAir gauging (±0.001 mm)

SPC softwareInfinityQS / Q-DAS qs-STAT

Target Cpk≥ 1.67 (critical dims.)

Gauge R&R≤ 10% TV (ANOVA method)

OOC responseAuto-stop + alarm within 1 cycle

Data retention3 years (ISO 9001 req.)

PROCESS CAPABILITY

Critical bore: Ø25.000 ±0.010 mm
USL = 25.010 | LSL = 24.990
Process mean x̄ = 25.002 mm
Process σ = 0.0028 mm
Cp = (USL-LSL)/(6σ) = 0.020/0.0168 = 1.19
Cpk = min((25.010-25.002)/3×0.0028, ...)
= min(0.95, 1.43) = 0.95 → IMPROVE!
Action: adjust feed to re-centre at 25.000

Project Deliverables & Timeline

Neo Materials delivers SPM projects on a fixed-price, fixed-timeline basis. Standard 12–20 week delivery from purchase order to machine acceptance at customer site. All deliverables are itemised in the contract before project start.

PROJECT TIMELINE

Week 1–2Concept design + customer review

Week 3–4Detailed CAD + BOM finalisation

Week 5–10Fabrication + component procurement

Week 11–14Assembly + wiring + PLC programming

Week 15–16FAT (Factory Acceptance Test)

Week 17–20Site installation + SAT + training

DOCUMENTATION PACKAGE

✔ 3D SolidWorks assembly model
✔ 2D GD&T drawings (all fabricated parts)
✔ Electrical schematic (EPLAN / E-plan)
✔ Pneumatic/hydraulic circuit diagram
✔ PLC program (source + backup)
✔ Operating & maintenance manual
✔ Spare parts list (BOM Level 1–3)
✔ Risk assessment (CE / IS 15658)
✔ Acceptance test protocol report

Design Your Special Purpose Machine

Share your part drawing and production target — Neo Materials will deliver a complete SPM concept with cycle time analysis, layout drawing, and budgetary quote within 5 working days.

Request SPM Concept