2.1 Machine Architectures

MachineThe choice of Pick-and-Place (PnP) architecture defines the characterDNA of ayour surface-mountSurface Mount Technology (SMT) line, setting the balancefixed trade-off between speed,raw flexibility,speed (CPH), component flexibility, and reliability.capital Whetherinvestment a(CapEx). lineYou leansare onessentially chipshooterschoosing forhow rawthe throughput,machine flexiblemanages mountersthe for range, or a hybridphysics of both,movement, the choicewhich dictates howtwo wellmajor itproduction keepsvariables: paceTakt with takt time. Motion systems, line topologies,Time and workloadChangeover balancing all fold into this architecture, determining whether production flows smoothly or stalls in firefighting. The right combination turns placement from a bottleneck into a stable backbone of manufacturing.Efficiency.

2.1.1 The Two kindsCore Architectures: Gantry vs. Turret

Modern high-speed placement machines primarily use one of pick-and-placetwo (andfundamental whymovement you’dsystems. mixChoosing them)between them determines your machine's optimal product mix.

TypeFeature	WhatModular/Gantry it’sSystems built(Flexible to doMounters)	Strengths	Trade-offs	BestRotary/Turret useSystems (Chipshooters)
ChipshooterMotion System	BlazingX-Y throughgantry, smallmoving passivesover (01005–0603),a somestationary small ICsboard.	VeryRotary highhead parts/hour;spins tiny-partcomponents vision;past lowstationary cost per placement	Narrower part range; changeovers hurt if you swap feeders often	High-volume boards with lots of repeat passivesvision.
FlexiblePlacement mounterSpeed (CPH)	Moderate to High.“Anything you throw at it” (BGAs/QFNs/QFPs,Up odd-form,to tall80k parts)CPH per module)	Extremely High.Broad component(Often range;≥ accurate;100k easierCPH) NPIin pure chip mode)
Component Range	Excellent. Handles everything from 01005 to large, odd-form, heavy connectors, QFPs, and BGAs.	Limited.Lower headlineBest speedfor onsmall tinypassives chips(01005 – 0603). Struggles with heavy/large ICs.
Placement Accuracy	Superior. Uses linear encoders and dedicated Z-axis control. Essential for ≤ 0.4 mm pitch.	GoodMixed-tech boards;but NPIgenerally lower for large components due to high speed/inertia.
Changeover Time	Fast. Component swap is typically managed via smart feeders/cart changes.	Slow. Fixed feeder banks mean high cost/time for swapping parts not in the bank.
CapEx/Flexibility	High CapEx initially, but excellent scalability (add modules/gantries) and variantflexibility builds(high-mix capability).	Lower CapEx per placement, but fixed capability and poor high-mix performance.

HouseStrategic rule:Takeaway: ifIf volumeyour justifiesEMS it,business is High-Mix/Low-Volume (HMLV) with frequent product changeovers, you want Flexible Modular/Gantry systems. If you run one board for weeks/months (High-Volume/Low-Mix), a chipshooter → flexibleTurret pair.system Ifis you’rethe high-mix/low-volume,most twocost-effective flexiblesway into parallelget beatsheer onespeed ofon each—fewer changeovers and simpler kitting. (We’ll tune programs in 8.2 and feeders/splicing in 8.3.)passives.

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2.1.2 HeadsLine &Topologies: motion: gantry vs turret

Architecture	How it moves	Why lines love it	Where it bites
Gantry (moving head on X-Y; multiple nozzles)	Head sweeps over a stationary board; cameras under/over	Flexible parts range, great accuracy on BGAs/QFNs; modular (add heads/gantries)	Peak CPH lower than a pure turret; throughput depends on path planning
Turret (rotary wheel with many nozzles)	Wheel spins parts past vision → drops at speed	Insane chip speed; shines on dense passive fields	Limited tall/odd-form; setup sensitivity; notAligning the toolFlow forto large/heavyYour parts

Mix

ModernHow linesyou blurarrange the PnP machines in the line (hybridmust heads, dual-gantry modules), butmatch the board's component distribution and your required Takt Time.

1. Role Split (Chipshooter – Flexible)

• mindsetSetup: stillChipshooter helps(PnP1) youhandles designall high-volume passives, then the flow:board feedmoves tinyto partsthe whereFlexible Mounter (PnP2) for large/complex ICs.
• rateWhen it Wins: matters, feed complex parts where range and accuracy matter.

  
  

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  2.1.3 Line topologies (and when each wins)

  Topology	Sketch	When to pick it	Notes
  Single stream: Printer → PnP1 → Reflow	One mounter	Small boards, light BOMs, pilot/NPI	Simple, cheap; limited peak rate
  Tandem split: Printer → PnP A + PnP B → Reflow	Two mounters in series	Most common volume setup	Balance parts so cycle times match (±10%)
  Role split: Chipshooter → Flexible	Fast chips first	Boards dominated by thousands of small chips +and relatively few large parts. This maximizes speed by pushing the fast work to the fastest machine. Watch-Out: If the flexible mounter becomes the bottleneck (Constraint), the chipshooter sits idle waiting. Requires disciplined load balancing (see below). 2. Tandem Split (Flexible A – Flexible B) Setup: Two flexible mounters of similar capability run in series, splitting the component count roughly 50/50 When it Wins: The most common setup for HMLV. It simplifies feeder management (as parts can run on either machine), speeds up changeovers, and offers redundancy. Watch-Out: Requires symmetrical programming and near-perfect load balancing to avoid bottlenecking. 3. Dual-Lane / Parallel Processing Setup: The entire line (Printer, PnPs, Reflow) processes two PCBs simultaneously on two separate conveyor tracks, or the PnP machine internally handles two boards at once. When it Wins: Extremely short boards or highly aggressive Takt Time requirements where placement time is the constraint. Ideal for "pack-and-stack" products. Watch-Out: Requires twice the number of feeders or mirrored feeder setups for both lanes, significantly increasing kitting complexity and OpEx. 2.1.3 Load Balancing: Protecting Your Takt Time The line Takt Time is always set by the slowest process step (the Bottleneck). In a fewPnP ICs	Keepline, high-hitthis chipis feedersalmost permanent
  Parallelalways lanesthe / dual-lane	Two lanes through sameplacement machine	Short boards,with tightthe TAKT	Greathighest forcomponent pack-and-stack, but needs disciplined feeder mirroring
  Top/Bottom mirror	Two lines per side	Dense double-sided builds	Sync changeovers; share feeder banks where possible

  Conveyors/buffers and handshakes live in 8.4; keep them smooth so mounters never starve.

  
  

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  2.1.4 When to splitcount or load-level (the 10-minutelargest math)

  variety of parts.
  1. Measure and Compare: eachUse machine’the machine's logging data (or a simulation tool) to calculate the placement time per board fromfor logseach (excludemachine, excluding board travel)travel time.
  2. Target 10% Symmetry: Your goal is for the cycle times of all PnP machines in the line to be within ± 10% of each other.
  3. The Fix: If PnP2 is 20% slower than PnP1, re-allocate the simplest, highest-count parts (e.g., 10kΩ resistors or common 100 nF caps) from PnP2 back to PnP1 until the times equalize.
  4. Protect the Constraint: Once balanced, treat the slowest machine (your current Takt constraint) as sacred. Never add more difficult parts or increase its feeder change frequency.

  Uptime Rule: Maximize Permanent Feeder Banks. By keeping 80% of your common components (like 0402 passives) in fixed slots, you massively reduce the time and risk involved in every single changeover, cutting down on OpEx and kitting errors.

  2.1.4 Strategic Feeder Management

  Feeder capacity and changeover are the daily operational killers.

  • Feeder Density: Gantry systems generally offer higher feeder capacity per machine footprint than older turret systems, allowing you to run boards with higher complexity (more unique part numbers).
  • FindSmart the bottleneck—the slowest station sets line TAKT.
  • Move part familiesFeeders: Invest in Intelligent Feeders. These communicate their Part ID (usuallyPN) passives)and fromposition the slow machineback to the fastmachine onesoftware, untilvirtually theireliminating timesthe risk of mis-kitting (placing the wrong part).
  • Kitting Carts: Use dedicated kitting carts or exchange trolleys so the feeders for the next job are withinprepared ±10%offline, allowing the changeover time to drop from hours to minutes.

  Conclusion:. Match your PnP architecture to your business model. High-volume stability demands turret speed, while the high-mix complexity of an EMS environment requires the

• flexibility, rapid changeover, and superior accuracyIf you can’t balanceoffered by parts, considermodern duplicate programs in parallelGantry/Modular (twosystems. similar mounters doing half the placements each).
• Re-run a First Article after any big split to confirm offsets/rotations stayed sane (that’s 8.5).
  

Think like line balancing: shift work off the constraint and protect it with feeder discipline. (Part VI digs deeper into bottlenecks and sustained throughput.)




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2.1.5 Practical rules that keep uptime high

• Permanent banks: park high-runner passives on fixed feeder banks; variants “hot-swap” the odd parts. (Feeder care/splicingDiscipline in 8.3.)
• Teachload for success:balancing lock vision teaching & rotation sanity during program creation so either machine can place the part without edits. (8.2)
• Don’t ping-pong boards: minimize unnecessary flips/returns; if you must split by side, keep symmetrical feeder layouts so changeovers feel the same on both lines.
• Buffers beat stars: small in-line buffers before the bottleneck absorb micro-stops and keep TAKT steady. (8.4)
  




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2.1.6 Quick chooser (print this)

• Mostly chips, few ICs → Chipshooter + Flexible in series.
• High-mix, many changeovers → Two Flexibles (parallel/tandem), permanent passive banks.
• Short boards, aggressive TAKT → Dual-lane with mirrored feeders.
• Fragile BGAs, many QFNs → Bias toward gantry heads for accuracy; keep chip load reasonable there.
  




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Well-matched machines, disciplined load balancing, and feeder strategies ensure uptime is protectedwhat andturns taktthis ishardware metinvestment withoutinto surprises.sustained By aligning architecture with product mix, the line runs predictably, with higher throughput and fewer interventions. throughput.