Machine Types — Dual-Drive vs. Single-Drive
Wire-pushing and paper-pushing are controlled by two independent motors. Both drives can be synchronized or operated separately. Stack height changes for different products only need to be set once in the control panel — no mechanical re-adjustment.
- Prevents wire flattening by syncing wire and paper feed precisely
- Supports both fixed and movable guide strip modes
- Required for two-stage insertion (push + pull-back with movable guide strips)
- Higher flexibility — accommodates wider wire gauge range
- Preferred for large-diameter wire (≥ 0.8 mm) or high slot fill (≥ 70%)
⚙️
Single-Drive Machine
单动力嵌线机
Wire and wedge paper are pushed together by a single motor via a shared mechanical linkage. When switching to a product with a different stack height, the mechanical coupling must be re-adjusted manually, adding changeover time.
- Simpler mechanical structure — lower cost, easier maintenance
- Suitable for standard wire gauges with moderate slot fill (≤ 70%)
- Stack height changeover requires physical re-adjustment
- Cannot independently control wire vs. paper feed timing
- Not suitable for movable guide strip (two-stage) insertion mode
6 Quality Factors — What Controls Insertion Quality
1
📏
Guide Strip Gap (导条间隙)
The gap between guide strip blades through which wire must pass. Set by slot opening width and blade lip thickness. Cannot be changed without tooling modification.
External
2
📊
Slot Fill Rate (槽满率)
Total copper area ÷ available slot area. Determined by motor design (turns, wire gauge). Practical limit: ≤ 80% for horizontal inserting machines.
External
3
🔩
Push Head Height (铜头高度)
Height of the nylon and auxiliary push heads. Affects how far wire is driven into the slot. Must match motor stack height. Adjustable on machine.
Equipment
4
📍
Guide Strip Position (导条位置)
Radial and axial position of guide strips relative to the stator bore. Must be centered and aligned correctly. Misalignment causes wire scraping and enamel damage.
Equipment
5
✨
Surface Finish (光洁度)
Smoothness of push head surface, guide strip edge R angles, and storage strip. Burrs or rough surfaces damage enamel insulation. Polish with cloth wheel — never sandpaper.
Equipment
6
⚡
Wire Insertion Speed (推入速度)
Speed at which wire is driven into slots. Too fast increases friction and enamel damage risk. Too slow reduces productivity. Speed must be matched to wire gauge and slot fill.
Equipment
Guide Strip Gap (BG) — Formula & Configuration
Guide Strip Mode Comparison
ModeFixed only
Wire motionOne-pass push
Enamel stressHigher
Use caseLarge slots, low fill
ModeFixed + Movable
Wire motionPush then pull-back
Enamel stressLower
Use caseNarrow slots, high fill
RequiresDual-drive machine
Wire Entry Zones — 4 Insertion Situations
④
Multi-Wire Simultaneous
Multiple wires enter the slot simultaneously in a well-organised stack. Minimal resistance. Best process quality.
Zone A — Best
②
Cross-2 Wire Entry
Two wires enter crossing at an angle. Some resistance but wires can pass. Corresponds to yellow zone CF on insertion chart.
Zone CF — Marginal
③
Parallel-2 Wire Entry
Two wires enter side-by-side, pressing against each other. High push force required. Risk of enamel damage.
Zone BD — Difficult
①
Single-Wire Queuing
Wires queue one-by-one — typical when slot is narrow and wire is thick. Push resistance very high. Enamel damage likely at >70% slot fill.
Worst Case
Blade Gap Angle Rule (US standard): When the entry angle N is between 18°–45°, wires are in the lock-up caution zone — enamel wire entry becomes difficult and enamel damage risk rises significantly. Blade gap = Tooth width. Min lip width = 0.012 in. Avoid lock-up area.
5-Component Tooling — Inspection & Maintenance
Slot Fill Rate — Critical Limit
Machine Limit
80%
Maximum for horizontal inserting machines
What happens above 80% slot fill
Wire breakage (断线) — excessive push force snaps conductors during insertion
Enamel insulation damage (漆皮破损) — friction between wire and guide strip edge tears the coating
Low process yield (工序合格率低) — high scrap rate, rework, and costly downstream failures
Wire flattening (严重扁线) — large-diameter wire (>0.8 mm) especially prone when slot opening is 2.1–2.2 mm and blade gap is insufficient
HiPot failure — enamel damage found only at final electrical test — rework or scrap of a fully assembled stator
Guide Strip Arc Edge — R Angles (Critical Contact Zones)
Critical R Points on Guide Strip Edge
R0.1
Inner top arc — Primary wire contact zone. Wire enamel slides directly across this surface during every insertion. Must be precisely R0.1 with consistent geometry across all 24 guide strips. Any deviation → uneven friction → enamel damage on specific strips.
R0.6
Outer arc — Secondary contact zone. Wire also touches this surface when entering at a shallow angle. Must be smooth and consistent. Chips or irregular radius → scratching during high fill rate insertion.
30°
Blade entry angle — The angled face that guides wire into the slot. Angle and surface finish at this face directly affect the wire entry zone (A/B/C/D) for a given wire diameter and gap.
✓ OEM Guide Strip — 4 Steps
1
粗打磨 — Rough grinding (initial shaping)
2
角度尺寸修正 — Angle dimension correction (ensures R0.1 consistent across all 24 strips)
3
羊毛毡镜面抛光 — Wool-felt mirror polishing
4
油石打磨 — Oilstone grinding (final micro-finishing)
Oilstone grinding reduces entry resistance and increases durability. Angle correction ensures all 24 guide strips are geometrically identical.
⚠ Subcontract Factory — 2 Steps Only
2
羊毛毡镜面抛光 — Wool-felt mirror polishing
Looks identical visually and works fine for standard wire. For thick wire (≥ 0.8 mm) or high slot fill (≥ 70%): pinhole currents, enamel micro-cuts, HiPot failures. R0.1 inconsistent across strips — some strips cause damage, others do not.
Case Study — ∅0.86 mm Wire: Why Changing the Gap Alone Isn't Enough
Gap = 1.20 mm · Wire = ∅0.86 mm · G/D = 1.40
23.29°
Entry angle at the blade opening. Although 1.2 mm is theoretically better than 1.4 mm for this wire, the angle still falls inside the lock-up caution zone. Wire insertion is still difficult. This is the gap achievable by modifying the lip guard to 1.1 mm.
Gap = 1.40 mm · Wire = ∅0.86 mm · G/D = 1.63
38.90°
Current production gap (standard 0.3 mm lip guard). Angle is 38.90° — squarely inside the lock-up zone (18°–45° caution range). Wire pairs jam against each other during insertion. This is why the XD-250SXL (∅0.96 mm wire) sees high enamel damage rates.
Key insight: Guide strip gap is a basic factor but NOT the only one. Even with an optimised gap, the result depends equally on push head angle, guide strip arc R radius, surface finish quality, and insertion speed. Every product change involving significantly different wire gauge requires calibration and run-in time on the machine. The blade gap chart gives the starting point — all the other factors determine whether you actually reach Zone A or stay in Zone B.
Counter-measures — 3 Options for Large-Diameter Wire (≥ 0.8 mm)
1
Modify Guide Strip Gap to 1.1 mm
For ∅0.8–0.9 mm wire, change the lip guard thickness from 0.3 mm to a value that achieves a ~1.1 mm blade gap. Theoretically shifts entry angle to ~23°. Limitation: only single-wire queuing entry is possible at this gap — the machine enters one wire at a time, so push force per wire is very high and setup time per product changeover is long.
Feasible now — tooling modification only
2
Upgrade to Dual-Drive Inserting Machine
A dual-drive machine (双动力嵌线机) gives independent control of wire feed and paper feed, enabling movable guide strip (活动导条) mode. The guide strips move with the wire — eliminating relative friction between wire and guide strip surface. Supports both staged two-phase insertion and thicker wire gauges.
~¥500,000 RMB per machine
3
Integrated Winding + Inserting Machine
A combined 绕嵌一体机 performs winding and coil insertion in a single automated cycle. Eliminates the manual transfer step between winding and inserting. Higher throughput and consistency.
~¥800,000 RMB per machine · Saves ~3 operators/shift
For slot fill > 73%: Use main/sub sequential insertion (主副分嵌) combined with movable guide strips. Insert the main phase (主相) first, then expand the stator to its maximum bore diameter before inserting the sub-phase (副相) — the extra space significantly reduces sub-phase entry resistance. This approach also requires adjustment of the forming and expanding machines (see below).
High Slot Fill Strategy (Fill Rate > 73%) — 3 Process Adjustments
3.1
Insertion — Movable Guide Strip Mode (主副分嵌 + 活动导条)
Mount the guide strips directly on the push head so they travel with the wire into the slot. This eliminates relative sliding friction between wire enamel and guide strip surface — the main cause of enamel damage at high fill. The principle is the same as a dual-drive machine: wire and guide move together. Insert main phase coils first (主相), then sub-phase (副相). Expand stator bore between phases to create clearance.
3.2
Forming Machine — Switch to Nylon Fixtures
High slot fill means more copper in the end-turns, producing larger and stiffer coil over-hangs. During forming, standard metal forming petals (涨瓣) apply too much local stress and can cause wire scratches on high-fill stators. Solution: replace the expanding petals and fixtures with nylon (尼龙) material. Nylon deforms slightly, distributing force more evenly without hard metal-to-enamel contact.
3.3
Expanding Machine — Two-Stage Expansion
When inserting sub-phase coils, the main phase already occupies part of the stator bore — reducing the effective clearance and increasing resistance on the sub-phase coils as they enter. To compensate: after inserting the main phase, expand the stator to its maximum allowable bore size using the expanding machine's guide teeth and retaining strips. This maximises the available space for the sub-phase and reduces the risk of enamel damage during its insertion.
Improvement Case — Winding Machine Mold Polishing
Before — Problem
The vertical winding machine (立绕机) mold surface had burrs and rough edges. As enamel wire passed over the mold during winding, these micro-edges scratched through the insulation coating — creating pinhole damage invisible to visual inspection.
Leakage current: 28 mA
After — Fix
The mold surface was polished (抛光) to a mirror finish — same process as the guide strip cloth-wheel polishing. All burrs and rough transitions removed. Wire now flows over the mold surface without any contact damage.
Leakage current: 0 mA
Reference — Slot Fill Data by Product (Washing Machine Stators, Wolong)
Standard horizontal inserting machines: effective range ≤ 80%. Products above ~73% fill start requiring special process handling. Red rows = problematic fill rate.
| Product |
Main Coils (large+small) |
Sub Coils (large+small) |
Wire Dia (mm) |
Main Fill (large/small) |
Sub Fill |
| XD-160SXL | 63 + 39 | 64 + 40 | 0.86 | 69.54% / 68.18% | 69.09% |
| XD-250SXL ⚠ | 55 + 34 | 56 + 35 | 0.96 | 74.59% / 73.24% | 74.38% |
| XD-180AL7 | 150 + 70 | 150 + 70 | 0.63 | 67.08% / 70.06% | 70.06% |
| XD-150ALLI | 208 + 98 | 214 + 107 | 0.52 | 68.99% / 68.78% | 70.44% |
| XDT-30AL | 305 + 145 | 295 + 150 | 0.41 | 70.27% / 69.13% | 67.27% |
| Stator production data (200W / 160W washing machine motors) |
| 200W Stator ⚠ | 55 + 34 | 56 + 35 | 0.90 | 74% | 74% |
| 160W Stator ⚠ | 63 + 39 | 64 + 40 | 0.80 | 73% | 73% |
Industry context: Standard washing machine aluminum wire range is 0.3–0.65 mm. For wire > 0.8 mm, horizontal inserting machines struggle: the 2.1–2.2 mm slot opening is fixed, so blade gap is insufficient for smooth entry. Results: wire insertion difficulty, enamel damage, severe wire flattening (严重扁线). These products require special process measures (Options 2 or 3 above, or main/sub sequential insertion).