Turn a shiny finish to a matte finish, or frost a clear part to diffuse light or make it translucent. MicroBlasting is an effective process for altering the finish on a base material by texturing. This process is widely used to enhance the adhesion characteristics of a surface for bonding or to modify the surface for cosmetic reasons.

Where Used

Medical

  • Angioplasty balloons
  • Cannulae – selective texturing of the tube surface prior to over-molding and light abrading to impart an echogenic or etched surface finish
  • Catheters – preparing surfaces to promote bond and coating adhesion
  • Lens molds
  • Molds
  • Nitinol stents
  • Orthopaedic implants
  • Pacemakers
  • PEEK implants
  • Vascular stent

Dental

  • Brackets
  • Orthodontic bands
  • Implants – roughening the threads increases the surface area for the tissue to take root, improving osseointegration
  • Surface prep of alloys prior to opaquing
  • Veneers

Aerospace

  • Bonding HUD optics
  • Connectors
  • Injection mold cavities – texturing the surface of a cavity on a new mold to hide splay lines, flow lines, knit lines, blush marks and other molding flaws
  • Load cells

Electronics

  • Connectors
  • Flex circuitry – texturing provides adhesion enhancement for bonded components and increases the peel strength of material when it is attached to other substrates
  • High performance capacitor cans

Industrial

  • Laser flow tubes
  • Load cells
  • Solar glass – texturing to increase reflectivity on backside
  • Underwater fiber optic cables

Automotive

  • Load cells – texturing surface for better bond adhesion
  • Molds

How To

MicroBlasting produces accurate and uniform surface finishes. Surface finish creation begins with identifying the ideal surface properties to achieve and then selecting the best abrasive for the job. Three factors impact surface finish creation:

Type of Media

The chemical and physical properties of abrasive affect surface finish. For instance, angular materials will leave a matte finish and spherical media will leave a satin finish. The more energy a media can store, the rougher the surface will be.

Size of Media

Larger abrasive create a rougher finish. As the mass of a particle increases, it leaves larger pits in the surface.

Speed of Media

Media speed is determined by blast pressure, nozzle design, propellant or gas type, and nozzle distance. For instance, a larger crater forms when the speed of the particle increases as it strikes the surface. This is typically the least understood variable.

Different materials will react differently to the blasting process.  These materials can be divided into two groups:

Ductile Materials

The Ra is a combination of the depth of the crater and the displaced ring around the edge. It is possible to use micro-abrasive blasting on a ductile material to produce either a satin or a matte finish.

Brittle Materials

There is no displaced ring. Ra is typically determined by the fracture mechanics and grain size of the substrate. Blasting on brittle materials only produces a matte finish.

Texturing Involves More Than Just Ra

Ra is simply a measurement of peak amplitude and does not measure density or spacing. These variables play a critical role in applications. Combining developed surface ratio with RA can provide a more accurate understanding of a surface’s properties. Mechanical bonds generally require more spacing between peaks; whereas organic bonds tend to require tighter spacing. Larger abrasives at lower pressure yield lower peak densities, and finer abrasives at higher velocities yield higher peak densities.

Learn more about surface texturing from Comco’s chief engineer Mickey Reilley in his presentation, “Microblasted Surface Finishes: How to Specify – How to Control.“

Manual/Automatic

Apply texture uniformly with either a manual or an automatic MicroBlasting system. A manual system is a great starting point. It gets you into the process. You can achieve desired results without having to invest heavily in fixturing and technology.

Automation is ideal for applications where large areas of a part need to be textured uniformly. MicroBlasting roughens these large surface areas without leaving lines or bands.

It also works particularly well on applications that require very tight tolerance or localized and focused texturing, like a dental implant that requires a sharp delineation between textured and non-textured areas.

Dental Implants

The surface texture of a dental implant determines how quickly and smoothly the implant integrates into a jaw bone. Needless to say, texture is a critical design component for any dental implant.

Studies indicate that the surface of the dental implant needs to be more than just rough. Several characteristics impact the rate of integration. MicroBlasting controls two of these characteristics: Ra, the size of the peaks and valleys; and the developed surface, or the amount of surface area created through the texturing process.

Automation achieves ideal results for surface texturing dental implants. Careful control over particle velocity and coverage creates a consistently uniform surface. Automated micro-abrasive blasting can create surfaces as smooth as 10 micro-inches or as rough as 200.

While surface texturing with MicroBlasting is most commonly used on bone screws and dental implants; it is appropriate for most implants that depend on a rapid fixation process, even some spinal implants.

Load Cells and Flexible Circuitry Bonding

Load cells and flexible circuitry need to bond to a metal substrate, either chemically or mechanically. MicroBlasting suits both applications, and each application can be done manually or using an automated system.

CHEMICAL BONDING

MicroBlasting roughens the surface of the load cell to keep it glued to the substrate.

MECHANICAL BONDING

MicroBlasting improves gripping power by creating large peaks and valleys on the flexible circuit.

Sodium Bicarbonate, is effective at roughening polyimide film, like Kapton. Sodium Bicarbonate is water soluble and easily washes off the device during the cleaning process.

Rework Injection Molds

Molds gradually lose their surface finish in production. Some molded parts change appearance and stick in the mold. Proper mold maintenance extends the life of mold cavities significantly.

The blasting process creates a uniform finish without degrading the mold cavity. The focused abrasive stream of a Comco blaster, like the AccuFlo®, delivers consistent results, especially on smaller and more intricate molds.

Glass Bead is an effective abrasive for this application. Its spherical shape forms smooth craters in the mold cavity and cleans out any residual material.

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