How to protect non-blast areas for Dalian blasting

Dalian Blasting Processing: Protection of Non-blasting Areas

Blasting removes rust, roughens surfaces and descales workpieces by high-speed abrasive impact. The abrasive carries strong impact force; unprotected areas are prone to scuffing and scratching. Many precision parts, finished components, threaded holes and fitting surfaces only require partial blasting. In Dalian blasting processing, suitable masking solutions are selected according to workpiece material, shape of protected zones, blasting pressure and abrasive type. Full-process control covering masking material selection, application, in-process protection, post-blasting removal and inspection prevents abrasive damage on non-blast surfaces.

Selecting masking materials based on working conditions is the foundation for protecting non-blasting areas in Dalian blasting processing. Common masking materials include rubber sheets, high-temperature blasting tapes, self-adhesive rubber sheets, silicone plugs, plastic stoppers and metal cover plates. Thickened blasting-specific rubber tape is preferred for regular flat areas. Ordinary masking paper and thin tapes have poor impact resistance and are easily penetrated under high-pressure blasting, so they are not suitable for prolonged blasting operations. Silicone plugs and rubber stoppers are fitted tightly into threaded holes, pin holes and internal threads to block abrasives. Cuttable rubber sheets secured with clamps are used for special-shaped curved surfaces and irregular contours. Custom reusable metal fixture covers are adopted for mass-produced standard workpieces for stable protection. Dry and wet blasting environments are distinguished in Dalian blasting processing. Water-resistant masking materials with stable adhesion are used for wet blasting to avoid glue lifting caused by moisture.

Pre-treatment of workpieces before masking ensures firm bonding of masking materials. Before applying protective materials in Dalian blasting processing, oil, dust and oxide scale on the surfaces to be masked are cleaned. A clean, dry surface enables tight adhesion of tapes and rubber sheets and reduces edge lifting and sand penetration. Oil contamination greatly weakens bonding strength, allowing abrasives to seep through gaps during blasting and cause edge erosion and blurred boundaries. For workpieces requiring marking, blasting boundaries are clearly marked in advance, and masking materials are aligned precisely along the marked lines with reasonable margins to avoid jagged, irregular dividing lines after blasting.

Zoned masking is implemented with differentiated treatment for different structures. For key protected areas such as threads, precision shaft surfaces, sealing grooves, electroplated surfaces and polished surfaces in Dalian blasting processing, dual protection combining plugging and outer covering is prioritized. Matching rubber plugs are pressed into small threaded holes; rubber gaskets with fasteners are used for large-diameter flange sealing surfaces. Thickened blasting tape is fully applied and fixed at both ends for long precision stepped surfaces. Baffles are used to block inner cavities and channel openings that do not require blasting to prevent rebounded abrasives from damaging inner walls. Masking fixtures shall not squeeze thin and easily deformable workpieces to avoid deformation; protection boundaries are kept away from stress concentration areas as much as possible.

Matching blasting process parameters reduce the risk of masking layer penetration. Uniform high-pressure parameters are not adopted in Dalian blasting processing. For workpieces with large masked areas, blasting pressure is appropriately reduced and gun distance adjusted to lower continuous abrasive scouring on masking edges. The spray gun is kept perpendicular to target blasting surfaces as much as possible. Long-duration oblique spraying toward masking edges is avoided, as oblique abrasive impact easily lifts tape edges and causes sand infiltration. Operators control the gun moving speed and avoid staying at masking boundaries for long to prevent local energy concentration. Spacing is reserved between mass workpieces during placement to prevent rebounded abrasives from damaging protected areas of adjacent parts.

Removal and inspection after blasting verify protection performance. Floating sand on workpiece surfaces shall be blown off before removing masking materials after blasting. Forcible tearing of tapes with sand trapped is forbidden to prevent scratches on finished surfaces caused by sand grains between glue and workpieces. Peel slowly along the bonding direction during removal to avoid peeling off brittle coatings together. After masking removal in Dalian blasting processing, boundary areas are checked for sand penetration, edge erosion and scratches. Threads and sealing surfaces are inspected for embedded sand grains, and compressed air is used to purge sand inside holes. Records are made for local sand penetration damage to optimize masking methods for subsequent batches, such as using thicker tape and adding more compression points.

Masking materials are recycled and managed to control processing costs. Silicone plugs, metal fixtures and thick rubber sheets can be reused after cleaning. Reusable protective parts are inspected for damage, aging and cracking before reuse; damaged ones are discarded directly. Disposable blasting tapes are stored by thickness specifications and pre-cut according to workpieces to improve efficiency. For long-term fixed orders, dedicated masking fixtures are designed preferentially in Dalian blasting processing. Compared with repeated taping, they deliver neat boundaries, better protection stability and shorter masking time per piece.

With proper masking material selection, thorough surface cleaning, precise plugging and covering, and controlled blasting processes, Dalian blasting processing can separate blasting zones from protected surfaces clearly, effectively preventing scratches and roughening from abrasive impact, and meeting the precision and appearance requirements of partial blasting.