Appearance
A manufacturer of hydraulic cylinder tubes operates six BTA drilling machines producing 40–120 mm diameter holes, generating approximately 1,800 kg of steel chips per 16‑hour two‑shift day. The existing manual chip handling system causes frequent production stops for chip removal and creates safety hazards from hot, oil‑soaked chips on the shop floor. The company installs a centralized chip handling system with hinged steel belt conveyors at each machine feeding an underground drag chain conveyor to a central collection hopper, with a chip briquetting press recovering 400 litres of coolant per day. The system handles chip loads up to 300 kg/h per machine with 99.5% uptime, eliminates manual chip handling, and recovers $38,000/year in coolant through briquetting.
Chip Types in Deep Hole Drilling
| Chip Morphology | Typical Material | Conveyor Suitability | Evacuation Ease | Coolant Retention |
|---|---|---|---|---|
| Long stringy/ribbon chips | Low-carbon steel, aluminium | Poor (tangles in hinged belt) | Difficult (clogs tubes) | High (oil-soaked tangles) |
| Short helical (C-shaped) | Medium-carbon steel with chip breakers | Good (flows freely) | Good (flushed easily) | Moderate |
| Segmented/saw-tooth | Alloy steel, 42CrMo4 at high speed | Good | Good | Low |
| Broken/small chips | Cast iron, hardened steel | Very good | Excellent | Low |
| Fine powder/dust | Cast iron, graphite | Poor (falls through belt gaps) | Excellent (suspended in coolant) | Very low (needs filtration) |
| Needle/acicular chips | Titanium, stainless steel | Poor (bridges across belt) | Difficult | Low |
TIP
Chip morphology in BTA drilling is controllable through chip breaker geometry on the insert rake face. The target chip shape for trouble-free handling is the C-shaped or short helical chip, approximately 5–15 mm in length. If your BTA drilling produces long stringy chips, install chip breakers on the inserts or adjust feed parameters — this single change can eliminate 80% of chip conveyor clogging problems.
Chip Conveyor Types
| Conveyor Type | Chip Types Handled | Max Capacity | Max Length | Coolant Drainage | Maintenance | Relative Cost |
|---|---|---|---|---|---|---|
| Hinged steel belt | All chip types (best for stringy/long) | 5,000 kg/h | 30 m | Good (belt perforations) | Moderate (hinge pin wear) | Moderate |
| Drag chain (scraper) | Short, broken chips | 3,000 kg/h | 50 m | Poor (chips dragged in coolant) | Low | Low |
| Screw conveyor | Fine chips, sludge | 1,000 kg/h | 15 m | Very poor (chips immersed) | Moderate (screw flight wear) | Low |
| Magnetic conveyor | Ferrous chips only | 2,000 kg/h | 10 m | Good (magnets lift from coolant) | Low (no mechanical chain) | Moderate |
| Magnetic roller | Ferrous fines, dust | 600 kg/h | N/A (elevator) | Excellent (dry discharge) | Very low | Low |
| Vacuum conveyor | Fine, dry chips | 500 kg/h | 50 m+ | N/A (dry only) | Moderate (filter changes) | High |
| Tubular drag | Fine, granular chips | 5,000 kg/h | 60 m | Good (enclosed tube) | Low | High |
Conveyor Sizing Calculation
| Parameter | Formula | Example (40 mm BTA drill in steel) |
|---|---|---|
| Material removal rate | Q = π·D²·f·n / 4,000 | 96 cm³/min |
| Chip mass flow rate | ṁ_solid = Q · ρ / 1,000 | 0.75 kg/min = 45 kg/h |
| Chip bulk density factor | ρ_bulk = ρ / K_exp | ~1.3 kg/L for steel swarf (K_exp = 6) |
| Chip bulk volume flow | V_bulk = ṁ_solid / ρ_bulk | 0.58 L/min = 0.035 m³/h |
| Fill factor on conveyor | k = 0.6–0.8 for hinged belt | Use 0.7 |
| Belt width | w ≥ 3× max chip length | 200 mm (for 50 mm max chip) |
| Belt speed | v = V_bulk / (w · h · k · 60) | 0.5 m/min (at h = 50 mm material height) |
| Drive power | P = F · v / (60 · η) | 0.37 kW (at F = 450 N chain pull) |
Fleet Capacity Example (6 machines, 40–120 mm drills)
| Machine | Drill Dia. | Avg MRR | Chip Mass Flow | Conveyor Capacity Required |
|---|---|---|---|---|
| Machine 1 | 40 mm | 96 cm³/min | 45 kg/h | 250 kg/h (with 5× safety factor) |
| Machine 2 | 60 mm | 216 cm³/min | 101 kg/h | 300 kg/h |
| Machine 3 | 80 mm | 384 cm³/min | 180 kg/h | 350 kg/h |
| Machine 4 | 80 mm | 384 cm³/min | 180 kg/h | 350 kg/h |
| Machine 5 | 100 mm | 600 cm³/min | 280 kg/h | 400 kg/h |
| Machine 6 | 120 mm | 864 cm³/min | 405 kg/h | 500 kg/h |
| Main conveyor | Central collection | — | 1,191 kg/h | 2,500 kg/h (with safety factor) |
Conveyor Selection Guide by Machine Type
| Machine Type | Typical Chip Shape | Recommended Primary Conveyor | Recommended Secondary | Why |
|---|---|---|---|---|
| BTA drilling (steel) | Short helical, segmented | Hinged steel belt | Magnetic separator | Handles all chip sizes, good coolant drainage |
| BTA drilling (cast iron) | Fine, powder | Magnetic conveyor | Paper band filter | Magnetic removes ferrous, band filter catches non-ferrous |
| Gun drilling (steel) | Fine, short chips | Scraper (drag) conveyor | Cartridge filter | Low chip volume, high coolant flow |
| Gun drilling (aluminium) | Fine, sticky chips | Scraper conveyor with anti-clog coating | Bag filter | Aluminium sticks to steel belts |
| Ejector drilling | Segmented, short | Hinged steel belt | Hydrocyclone | Higher chip volumes, need pre-filtration |
| Trepanning | Large arc chips | Heavy-duty hinged belt (HARDOX lined) | None needed (large chips only) | Extreme chip weight, wear-resistant construction |
Integrated Chip Conveyor and Coolant Filtration Systems
| System | Conveyor Type | Filtration Method | Filtration Rating | Flow Capacity | Key Advantage |
|---|---|---|---|---|---|
| Mayfran ConSep Flex | Hinged belt + drag chain | Self-cleaning drum filter | 50 µm (10 µm with AT-Cleaner) | Up to 4,000 L/min | Three-in-one: belt, scraper, magnetic bed |
| Jorgensen EcoFilter | Hinged belt | Wedgewire filtration cell + CleanCleat brushes | 30–50 µm | Up to 3,000 L/min | No consumable media, self-cleaning |
| Hennig CFC | Hinged belt | Paper band filter | 15–25 µm | Up to 2,000 L/min | High filtration precision |
| LNS Turbo | Scraper conveyor | Magnetic drum + cartridge | 10–25 µm | Up to 1,500 L/min | Compact footprint |
| FAMA Chip Conveyor | Hinged belt or scraper | External filter unit (optional) | 20–50 µm | Up to 5,000 L/min | Modular, customizable |
WARNING
Never size a chip conveyor based on average chip flow alone. Deep hole drilling produces intermittent chip bursts — especially during drill entry, when exiting the workpiece, or when drilling through interruptions (cross holes, keyways). Size the conveyor for 150–200% of the calculated peak chip flow. A conveyor that runs at 50–70% of its rated capacity under average conditions will handle burst loads without jamming and will have a significantly longer service life than one run continuously near its limit.
Central Chip Handling System Design
| Component | Function | Sizing Guideline | Typical Specification |
|---|---|---|---|
| Machine-level conveyor | Transfers chips from each machine to main conveyor | Per machine chip flow × safety factor 2× | Hinged steel belt, 200–500 mm wide |
| Main collection conveyor | Gathers all machine chip flows to central point | Fleet chip flow × safety factor 1.5× | Drag chain or hinged belt, 400–1,000 mm wide |
| Central hopper | Buffers between conveyor and processing | ≥ 1 shift of chip storage | 5–20 m³ capacity, sloped bottom (60° min) |
| Chip shredder | Reduces chip size for downstream processing | Rated for peak chip flow | Single or dual-shaft, 10–50 HP |
| Centrifuge | Separates coolant from chips | Residence time 30–60 s | 100–2,000 kg/h capacity |
| Briquetting press | Compresses chips into dense briquettes | Compression ratio 6–8:1 | 200–5,000 kg/h, 95% coolant recovery |
| Coolant recovery tank | Collects recovered coolant from centrifuge/briquetter | ≥ 1,000 L | Return to main coolant system |
Chip Processing Options
| Method | Output Form | Coolant Recovery | Volume Reduction | Energy Consumption | Capital Cost |
|---|---|---|---|---|---|
| Direct disposal (skip/bin) | Loose wet chips | 0% | 1:1 | None | Very low |
| Wringer/centrifuge only | Damp chips (5–10% oil) | 60–80% | 2–3:1 | 5–15 kWh/tonne | Moderate |
| Centrifuge + shredder | Shredded damp chips | 70–85% | 3–5:1 | 15–30 kWh/tonne | Moderate |
| Briquetting press | Dry briquettes (< 3% oil) | 90–95% | 6–8:1 | 25–50 kWh/tonne | High |
| Full system (shred + centrifuge + briquette) | Dry dense briquettes | 95%+ | 8–10:1 | 40–80 kWh/tonne | Very high |
Chip Handling Economics
| Item | Manual Handling | Central Conveyor System | Central + Briquetting |
|---|---|---|---|
| Labour cost for chip removal | $45,000/year (1.5 FTE) | $3,000/year (supervision) | $3,000/year |
| Coolant loss in chips | $52,000/year (chips retain 20% coolant) | $52,000/year | $5,200/year (briquettes < 3% coolant) |
| Chip disposal cost (per tonne) | $50/tonne (wet chips, 50% coolant) | $50/tonne | $15/tonne (dry briquettes, higher scrap value) |
| Annual disposal cost (200 tonnes) | $10,000 | $10,000 | $3,000 |
| Maintenance cost | $500 | $4,000 | $6,000 |
| Energy cost | $0 | $2,500 | $6,000 |
| Total annual cost | $107,500 | $71,500 | $23,200 |
| System investment | $0 | $120,000 | $250,000 |
| Annual savings vs. manual | — | $36,000 | $84,300 |
| ROI period | — | 3.3 years | 3.0 years |
Maintenance Schedule
| Component | Daily | Weekly | Monthly | Quarterly | Annually |
|---|---|---|---|---|---|
| Hinged steel belt | Visual inspection for jams | Check belt tension | Lubricate hinge pins | Inspect hinge pins for wear | Replace worn belt sections |
| Drag chain conveyor | Check chain tension | Verify scraper condition | Clean sprocket area | Inspect chain links | Replace worn chain |
| Screw conveyor | Check for blockages | Verify bearing seals | Lubricate bearings | Check screw flight wear | Replace flight if worn |
| Drive motor | Listen for unusual noise | — | Check coupling alignment | Check motor current | Replace bearings |
| Coolant return pump | Verify flow | Clean strainer | Check seal condition | Replace seals if leaking | Overhaul |
| Chip centrifuge | — | Clean bowl if reduced efficiency | Check discharge chute | Inspect wear zones | Rebuild |
| Briquetting press | — | Check briquette quality | Inspect ram seals | Hydraulic oil change | Full overhaul |
| Central hopper | Monitor fill level | — | Clean internal walls | — | Structural inspection |
Troubleshooting Guide
| Symptom | Likely Cause | Diagnosis | Corrective Action |
|---|---|---|---|
| Conveyor jams repeatedly | Long stringy chips not broken by tool | Examine chip shape (target: 5–15 mm C-shape) | Adjust chip breaker geometry, increase feed rate |
| Belt stalls under load | Overload exceeding motor torque | Measure actual chip flow vs. rated capacity | Upgrade motor or reduce feed at peak conditions |
| Belt tracking off-centre | Uneven tension or worn guide rails | Check belt alignment marks, measure rail wear | Re-tension belt, replace worn rails |
| Excessive hinge pin wear | Abrasive chips (hardened steel, cast iron) | Measure pin diameter loss per 1,000 hours | Upgrade to HARDOX pins or hardened steel belt |
| Coolant leaking through belt | Belt perforations oversized for chip size | Check if chips should form filter cake | Install finer mesh belt section at return end |
| Conveyor reverses direction | Chip jam under returning belt | Check for obstruction at tail sprocket | Clear blockage, install anti-return clears |
| Chip carryover to coolant tank | Belt speed too high for chip settling | Measure belt speed vs. recommended | Reduce belt speed, increase tank residence time |
| Excessive vibration | Worn sprockets or damaged belt | Inspect sprocket teeth, belt links | Replace sprockets, repair belt section |
| Centrifuge out of balance | Uneven chip distribution in bowl | Check feed rate consistency | Install feed chute distributor, reduce feed rate |
| Briquette quality poor | Moisture too high (coolant content > 5%) | Measure coolant percentage in input chips | Pre-drain chips before briquetting, check centrifuge |
FAQ
What type of chip conveyor is best for BTA drilling?
Hinged steel belt conveyors are the best choice for BTA drilling. They handle the full range of chip types produced by BTA tools (short helical, segmented, and occasional stringy chips), withstand the heavy chip loads typical of BTA drilling (50–400 kg/h per machine), and allow high-pressure coolant to drain through the belt perforations. For machines with exceptionally high chip volumes, a heavy-duty hinged belt with HARDOX wear-resistant tracks is recommended.
How is conveyor capacity calculated for deep hole drilling?
Conveyor capacity is calculated from the material removal rate of the drilling process multiplied by a safety factor of 2–5×. The material removal rate depends on drill diameter, feed rate, and spindle speed. For a 40 mm BTA drill in steel at typical parameters, chip flow is approximately 45 kg/h, requiring a conveyor capacity of at least 200 kg/h. Additional margin is needed for chip burst loads during interrupted cutting and drill entry.
What chip shape is ideal for trouble-free handling in BTA drilling?
C-shaped or short helical chips of 5–15 mm length are ideal. These chips flow freely through the chip evacuation tube, do not tangle in the conveyor mechanism, and pack efficiently in collection bins. Chip shape is controlled by the chip breaker geometry on the BTA insert. If the process produces long stringy chips, try adjusting the chip breaker land width or increasing feed rate to promote chip breaking.
How does an integrated chip conveyor and coolant filtration system work?
Integrated systems combine a hinged steel belt conveyor for bulk chip removal with a built-in filtration stage. The hinged belt lifts chips out of the coolant flow while allowing coolant to drain through. The drained coolant then passes through a secondary filtration stage (drum filter, wedgewire screen, or paper band) to remove fine particles before returning to the coolant tank. Systems like Mayfran ConSep Flex and Jorgensen EcoFilter are designed for exactly this purpose.
What is the ROI of a central chip handling system?
For a six-machine BTA shop generating 1,800 kg/day of chips, a central chip handling system with briquetting recovers the investment in approximately 3 years. Annual savings come from eliminating manual chip handling labour ($42,000/year), coolant recovery through briquetting ($46,800/year), and higher scrap value for dry briquettes vs. wet chips ($7,000/year). Total annual savings of approximately $84,300 against a $250,000 investment.
How much coolant is lost in wet chips?
Wet chips from deep hole drilling typically retain 15–25% coolant by weight, depending on chip shape and material. For a shop processing 200 tonnes of steel chips per year, this represents 30–50 tonnes of coolant lost annually — equivalent to $45,000–75,000 at $1.50/litre. A chip centrifuge recovers 60–80% of this, while a briquetting press recovers 90–95%, reducing coolant loss to 3% or less in the briquettes.
What causes hinged steel belt conveyor jams?
The most common cause is long, stringy chips that wrap around the hinge pins and sprockets, preventing belt articulation. Other causes include: oversized chip accumulations that bridge across the belt width, foreign objects (tools, inserts) jamming between belt and housing, and worn hinge pins that allow belt misalignment. Regular inspection of chip shape (target: < 15 mm length) is the most effective prevention.
Can chip conveyors handle wet chips from high-pressure coolant systems?
Yes. Hinged steel belt conveyors are designed to operate submerged in coolant or to receive coolant-heavy chip flow. The belt perforations allow coolant to drain back to the tank while the chips are carried upward to the discharge point. The conveyors must be adequately sealed at the coolant tank penetration and equipped with a drip tray at the discharge end to contain coolant carryover.
What maintenance does a chip conveyor need?
Daily: visual inspection for jams, unusual noises, and coolant leaks. Weekly: check belt tension and clean any chip accumulation in corners. Monthly: lubricate hinge pins, check drive chain tension, and verify belt tracking. Quarterly: inspect hinge pins for wear and replace worn sections. Annually: complete drive system service including motor bearings, gearbox oil change, and coupling alignment.
Should chips be shredded before briquetting?
Shredding before briquetting is recommended for deep hole drilling chips. Long or stringy chips do not feed consistently into a briquetting press, causing uneven briquette quality. A single-shaft shredder reduces chips to 20–50 mm fragments that flow freely into the press feed hopper. For operations producing only short C-shaped chips (as is typical with well-adjusted BTA chip breakers), shredding may be skipped.
Summary
Chip conveyor and handling system selection for deep hole drilling must begin with chip morphology — the shape, size, and material of the chips produced by the drilling process. Hinged steel belt conveyors are the primary choice for BTA drilling, handling the full range of chip types and allowing coolant drainage through the belt. Conveyor sizing requires calculation of the material removal rate per machine with a 2–5× safety factor to handle burst loads during interrupted cutting. Integrated systems combining chip conveyors with coolant filtration (such as Mayfran ConSep Flex or Jorgensen EcoFilter) reduce equipment footprint and simplify maintenance. For fleet operations, a central chip handling system with underground drag chain conveyor, hopper, and chip processing (centrifuge or briquetting press) eliminates manual chip handling, recovers 90–95% of coolant from chips, and improves scrap value. The economic case for chip processing is compelling: a six-machine shop can save $84,000/year with a 3-year ROI through labour elimination, coolant recovery, and higher-value dry chip briquettes.