Appearance
A manufacturer of lipstick moulds drilled conformal cooling channels in a P20 tool steel insert (6 channels of 6 mm x 150 mm deep, positioned within +/-0.05 mm of cavity surface) using a carbide gun drill (6 mm, Vc = 100 m/min, f = 0.06 mm/rev, emulsified oil at 50 bar). Cooling channels reduced cycle time from 18 to 11 seconds (39% reduction) and improved lipstick surface finish by eliminating sink marks. Channel position verified by ultrasonic thickness measurement (+/-0.04 mm of nominal 4 mm distance).
Lipstick Mould Conformal Cooling Channels
Lipstick mould cooling channels are gun-drilled conformal channels that follow the contour of the mould cavity, providing uniform cooling to the solidifying lipstick bullet. The conformal cooling channels reduce the moulding cycle time by 30-50% compared to straight-drilled channels (which cannot follow the cavity contour). The gun drilling parameters for P20 mould steel are: carbide gun drill with TiAlN coating, Vc = 80-120 m/min, feed f = 0.05-0.08 mm/rev, emulsified oil at 40-60 bar. The channel diameter is 6-10 mm, the pitch between channels is 2-3x the diameter, and the distance from the channel to the cavity surface is 3-5 mm.
| Parameter | Lipstick Mould (P20 Steel) | Cosmetic Compact Mould (420SS) | Deodorant Ball Mould (P20) | Mascara Wand Mould (H13) |
|---|---|---|---|---|
| Channel diameter | 6-10 mm | 6-8 mm | 8-12 mm | 4-6 mm |
| Channel depth | 80-200 mm | 50-120 mm | 100-250 mm | 60-100 mm |
| Number of channels | 4-8 | 4-6 | 6-10 | 3-5 |
| Distance to cavity surface | 3-5 mm | 3-4 mm | 4-6 mm | 2-4 mm |
| Channel pitch | 15-25 mm | 12-20 mm | 18-30 mm | 10-18 mm |
| Gun drill type | Carbide, TiAlN coated | Carbide, TiAlN coated | Carbide, TiAlN coated | Carbide, TiAlN coated |
| Cutting speed (Vc) | 80-120 m/min | 70-100 m/min | 80-120 m/min | 70-100 m/min |
| Feed rate (f) | 0.05-0.08 mm/rev | 0.04-0.07 mm/rev | 0.05-0.08 mm/rev | 0.04-0.06 mm/rev |
| Coolant pressure | 40-60 bar | 30-50 bar | 40-60 bar | 30-50 bar |
| Cycle time reduction | 30-50% | 25-40% | 30-45% | 25-35% |
The channel position is verified by ultrasonic thickness measurement. The ultrasonic probe measures the distance from the cavity surface to the cooling channel at multiple points along each channel, typically 5-10 measurement points per channel. The measured distance must be within +/- 0.05 mm of the nominal value to ensure uniform cooling.
Perfume Nozzle Micro-Bores and Personal Care Component Drilling
Perfume bottle spray nozzle micro-bores are drilled in brass or stainless steel nozzle inserts. The nozzle has a micro-bore of 0.2-0.5 mm diameter x 5-15 mm depth, which atomises the perfume into a fine mist. The bore surface finish must be Ra less than 0.4 microns to ensure consistent droplet size and spray pattern. The drilling is performed using a PCD-tipped micro gun drill at Vc = 30-50 m/min, feed f = 0.001-0.003 mm/rev, oil coolant at 100-150 bar.
| Parameter | Perfume Nozzle (Brass) | Perfume Nozzle (SS) | Electric Toothbrush Shaft | Razor Handle Hinge Pin |
|---|---|---|---|---|
| Bore diameter | 0.2-0.5 mm | 0.2-0.5 mm | 2-5 mm | 1.5-3 mm |
| Bore depth | 5-15 mm | 5-15 mm | 80-120 mm | 15-30 mm |
| Material | Brass / Cupronickel | 303SS / 316SS | 304SS / Ti Grade 5 | Zinc alloy / SS |
| Drill type | PCD micro gun drill | PCD micro gun drill | Carbide gun drill | Carbide twist drill |
| Cutting speed (Vc) | 30-50 m/min | 20-40 m/min | 40-60 m/min | 60-80 m/min |
| Feed rate (f) | 0.002-0.003 mm/rev | 0.001-0.002 mm/rev | 0.02-0.05 mm/rev | 0.03-0.06 mm/rev |
| Coolant pressure | 100-150 bar oil | 120-150 bar oil | 40-60 bar oil | 20-40 bar oil |
| Surface finish (Ra) | < 0.4 microns | < 0.4 microns | < 0.8 microns | < 0.8 microns |
| Tolerance | +/- 0.01 mm | +/- 0.01 mm | +/- 0.02 mm | +/- 0.03 mm |
| Inspection method | Flow test + microscope | Flow test + microscope | Borescope + gauge pin | Gauge pin + CMM |
Electric toothbrush drive shaft bores are gun-drilled in stainless steel or titanium drive shafts for sonic toothbrushes. The bore provides a passage for the drive rod that transmits the ultrasonic vibration from the transducer to the brush head. The bore must be straight within 0.05 mm over the full length to prevent the drive rod from contacting the bore wall and damping the vibration.
Quality Control for Cosmetics Drilling
| Inspection Parameter | Method | Acceptance Criteria | Frequency |
|---|---|---|---|
| Cooling channel position | Ultrasonic thickness gauge | +/- 0.05 mm from cavity surface | 5-10 points per channel |
| Cooling channel diameter | Plug gauge | +/- 0.05 mm | Sample (per channel) |
| Nozzle bore diameter | Microscope (50x) | +/- 0.01 mm | 100% of nozzles |
| Nozzle surface finish | Profilometer (replica) | Ra < 0.4 microns | Sample (10%) |
| Nozzle flow rate | Flow bench at rated pressure | Within +/- 5% of design | 100% of nozzles |
| Toothbrush shaft straightness | Dial indicator / V-block | 0.05 mm over full length | 100% of shafts |
| Razor hinge pin bore diameter | Go/No-Go gauge | +/- 0.03 mm | Sample (10%) |
| Spray pattern test | High-speed video analysis | Uniform cone angle | Sample (per batch) |
Frequently Asked Questions
How do conformal cooling channels reduce lipstick mould cycle time?
Conformal cooling channels follow the contour of the mould cavity, providing uniform heat extraction from the solidifying lipstick bullet. In a conventionally cooled mould (straight-drilled channels), the cooling is uneven — the areas closer to the channels cool faster than the areas between them, causing the lipstick to shrink unevenly and develop sink marks. Conformal cooling channels maintain a constant distance from the cavity surface (typically 3-5 mm), providing uniform cooling that allows the lipstick to solidify 30-50% faster. In the case study, the cycle time dropped from 18 seconds to 11 seconds, a 39% reduction that translates to 320 more pieces per hour from a single-cavity mould.
What is the acceptable surface finish for a perfume nozzle micro-bore?
The acceptable surface finish for a perfume nozzle micro-bore is Ra less than 0.4 microns. This level of smoothness is required to ensure consistent atomisation — if the bore surface is rough, the perfume droplets form irregularly, producing an inconsistent spray pattern and varying droplet sizes. The surface finish is achieved by using a PCD-tipped micro gun drill (which provides the sharpest cutting edge) at low feed rates (0.001-0.003 mm/rev) with high coolant pressure (100-150 bar) to evacuate chips and prevent built-up edge formation.
How is the position of a cooling channel verified after drilling?
The position of a cooling channel relative to the mould cavity surface is verified using an ultrasonic thickness gauge. The ultrasonic probe is placed on the cavity surface, and the time-of-flight of the ultrasonic pulse through the steel to the channel wall is measured. The thickness is calculated from the sound velocity in the mould steel (typically 5900 m/s for P20 tool steel). Measurements are taken at 5-10 points along each channel, and the measured distance must be within +/- 0.05 mm of the nominal value.
What causes electric toothbrush shaft bore straightness problems?
Electric toothbrush shaft bore straightness problems are most commonly caused by drill wander — the gun drill deflecting off-centre as it enters the shaft material. The two main causes are: (1) the shaft end face is not perpendicular to the shaft axis (the drill enters at an angle, then tries to straighten, creating a curved bore), and (2) the material hardness varies along the shaft length (hard spots cause the drill to deflect). To prevent drill wander, the shaft end face is spot-faced flat before drilling, and the material hardness is verified by a spot hardness test at both ends of the shaft.
Can cosmetics mould cooling channels be added to an existing mould?
Yes, cooling channels can be retrofitted to existing injection moulds, but the process is constrained by the existing mould geometry. The new channels must be positioned to avoid existing cooling channels, ejector pin holes, and mould fastener holes. The minimum wall thickness between the new channel and any existing cavity or hole must be at least 2 mm. The drilling is performed on a CNC machining centre with the mould insert positioned using a 5-axis table to drill the channels at the correct angle to follow the cavity contour. Retrofitting typically costs 30-50% of a new mould insert.
The information provided in this article is for general informational purposes only. Data are based on published research and industry experience as of 2026. Always consult your mould maker or tooling supplier for application-specific parameters.