How to choose a suitable sandblasting machine for computer shell sandblasting?

Key points of selecting sandblasting machine for computer (notebook) shell

Computer housings are mostly 6061/6063 aluminum alloy thin-walled die castings. The purpose is to remove knife lines, parting lines and oxide scales, make uniform matte sand lines, and do pretreatment for anodizing and spraying. The wall of the workpiece is thin, and it is afraid of deformation, bruise and corner collapse. At the same time, aluminum dust has explosion risk, so it is necessary to give consideration to appearance yield, safety, environmental protection and productivity.

First, determine the automation level (by output)

Proofing, small batch (within several hundred pieces per day)

Select the box-type manual suction type environmental protection sandblasting machine, with turntable fixture and workpiece fixing fixture to prevent the workpieces from bumping against each other.

Don't use roller/crawler: the corner and surface of the shell will be bruised when the workpiece rolls and hits, and the yield is low.

Power priority suction type (negative pressure), the pressure is 0.2‑0.4MPa, and the impact force is soft to prevent the thin-walled shell from being deformed; Try to minimize the use of press-in high-pressure models.

Medium batch production (thousands of pieces/day)

Automatic sand blasting machine with priority rotary table, tooling fixture positioning shell, multi-swing spray guns spraying from multiple angles, the workpieces are stationary and rotate with the rotary table, no workpieces collide with each other, and the sand grain is uniform, which is suitable for complex shell, side and inverted position treatment.

Mass production line (tens of thousands of pieces/day)

Screen belt conveyor automatic sandblasting machine, multi-gun swing, frequency conversion speed regulation; Disadvantages: the bottom surface of the shell is easy to leak, which requires a turnover station. The shell must be limited by a special fixture to prevent collision.

Tip: Thin-walled parts of notebook shell are prohibited from crawler shot blasting machine, which is bound to be damaged and scrapped.

Second, dry vs wet, explosion-proof how to choose (safety key)

Dry explosion-proof sandblasting machine (aluminum shell mainstream)

Processing aluminum alloy will produce combustible aluminum dust, so ordinary non-explosion-proof sandblasting machine cannot be used.

Required configuration:

Explosion-proof motor, explosion-proof electric control, electromagnetic valve; The whole machine is reliably grounded, and the air duct flange is anti-static;

Anti-static PTFE coated filter cartridge for dust removal, with explosion-proof sheet; Automatic recovery and separation of abrasive cyclone.

Suitable for: pursuing efficiency and subsequent anodic oxidation; The working air pressure is controlled at 0.2‑0.4MPa, and fine sand blasting is carried out at low pressure to avoid shell deformation.

Wet (water blasting explosion-proof sandblasting machine)

Water wraps the abrasive, and the suspended metal dust is suppressed, so the explosion risk is the lowest; The impact force is buffered by water, and the thin-walled parts are not easy to be deformed, heated and blackened.

Disadvantages: the workpiece must be dried after sandblasting, and the efficiency is slightly lower than that of dry type; The texture of sand grain will be different from that of dry type, so the samples should be confirmed in advance.

Suitable for: magnesium alloy shell, ultra-thin shell with extremely high explosion-proof grade and shell wall thickness < 1.2 mm.

Third, the power form: suction vs press-in type

Suction type (negative pressure): the first choice for computer shell

The pressure is 0.2‑0.5MPa, the impact force is soft, and the sand content is stable and controllable, which is suitable for fine matte and roughening before anode, and it is not easy to thin and deform the shell. Suitable for fine-grained abrasives such as glass sand, ceramic sand and zirconium sand (120220 mesh).

Press-in pressure tank model: large impact force, only suitable for thick shell to remove thick oxide scale; Thin-walled notebook shell should be used with caution, and it is easy to deform and corner collapse when the pressure is slightly high.

Four, the equipment must pay attention to the key configuration

The pressure can be adjusted independently: each spray gun adjusts the pressure, and the large plane, corner and thin-walled area of the shell distinguish the pressure.

Swing mechanism of spray gun: swing speed can be adjusted by frequency conversion to ensure uniform sand grain of the whole shell and avoid local overspray.

Abrasive separation and recovery system: cyclone separation, which automatically separates and discharges the broken fine powder to prevent the broken sand from causing pockmarked scratches on the workpiece.

Fixture and fixture: the shell must be fitted with copying fixture, and the workpieces can't be piled up freely, so as to prevent bumping.

Dust removal: film-coated filter cartridge, filtration efficiency ≥99.9%, meeting the requirements of environmental assessment; Anti-static filter cartridge must be used in aluminum dust working condition.

V. Supporting process reference (synchronous confirmation when selecting equipment)

Abrasive: glass sand, ceramic sand, zirconium sand, commonly used 120 # 180 #, the larger the mesh number, the finer the sand grain.

Working pressure: 0.25‑0.35MPa, high pressure is strictly prohibited; If the pressure is too high, the shell will be deformed and the wall thickness will be reduced.

Air compressor: match the number of spray guns, and the air volume of suction single gun is ≥ 1.21.5 m/min.

Summary of rapid selection

Small batch of proofing: explosion-proof suction box sandblasting machine+turntable tooling

Small and medium batch production: explosion-proof rotary automatic sandblasting machine (suction type)

Mass production line: automatic sandblasting machine with explosion-proof mesh belt conveying, equipped with special housing fixture.

Ultra-thin/magnesium alloy shell: priority wet explosion-proof water sandblasting machine