Vacuum Metalizing Process Overview

Vacuum Metalizing is the process of evaporating metals (most commonly aluminum) inside a vacuum chamber which then bonds to the desired substrate to achieve a uniform metalized layer.

Thermal evaporation, otherwise known, as vacuum metalizing, is the most common PVD (Physical Vapor Deposition) process used to apply metal alloys under vacuum.

Vacuum metalizing has many uses including; EMI/RFI shielding, decorative chrome and metallic finishes, highly reflective coatings for light reflectors, heat shielding, vapor barriers, and more.

The different stages of the Vacuum Metalizing process are explained below.

Tooling Process

Our process begins with the fabrication of custom tooling fixtures to hold and mask your parts during the vacuum metalizing and painting operations.

We ensure tooling fixtures provide maximum efficiency both in the number of components on a fixture and the handling of the fixture for processing, which allows for the best possible piece price.

Our sister company Designers Metalcraft is a custom sheet metal fabrication job shop that services a wide range of industries including manufacturing holding fixtures such as the tooling fixtures utilized for Mueller Corporations vacuum metalizing and industrial coating services.

Designers Metalcraft has been in business since 1955 and brings a wealth of knowledge to cost effective, tight-tolerance tool making.
Capabilities include Laser Cutting, Water Jet Cutting, Precision Forming, Welding, Fabrication, and Finishing.

LOADING PROCESS

Next, tooling fixtures are inspected by our quality team and then released to production.

We follow guidelines set by the customer and adhere to strict to quality standards to ensure correctly processed parts. Operators wear gloves while loading the parts, so no contaminants are transferred to the parts.
Individual parts, inspected to ensure visible defects get resolved, are then loaded onto the tooling fixtures.

Our goal is to ensure masking is integrated into the tooling fixtures to minimize manual processes. Any masking that is not achievable with a tooling fixture will be completed before processing.

Basecoating Process

Basecoating Process

For most decorative and reflective applications it is necessary to apply a specially formulated primer or basecoat to promote adhesion and to provide a smooth surface, assuring a high-quality surface for the metalizing or finish paint steps.
This step is only needed for reflective finishes and chrome and metallic coatings and is not necessary for EMI/RFI shielding.

Mueller Corporation has developed proprietary coatings for many substrates, including flexible plastics, which are suited for both high and low-temperature applications.

All coatings are applied by High-Volume Low-Pressure Spray guns (HVLP) by three different methods including six-axis robotic paint cells, automatic reciprocating paint cells, or by hand for low volume and prototypes. Our robotic spray cells include eight bank color change which allows us to apply a variety of coatings needed for a job shop environment including conductive paint for EMI/RFI shielding, metallic paints, and basecoats and topcoats for vacuum metalizing. After paint application, the tooling fixtures are placed into convection ovens to cure the paint.

Vacuum Metalizing Process

First, the tooling fixtures get placed into Carousels that are moved into the vacuum chamber. A predetermined vacuum level is reached, and current is sent to the evaporation source.

The source is a tungsten filament loaded with alloy (most commonly aluminum). The current heats the filament until the alloy evaporates, which forms a vapor cloud that bonds to the parts.

Thermal evaporation of alloys is a line-of-sight process, so the tooling fixtures rotate in front of the evaporation sources to achieve a uniform coating. Upon completion of the metalizing process, the chamber is returned to atmosphere, and the tooling fixtures are unloaded.

Our proprietary EMI/RFI shielding process allows us to evaporate over 25 microns of aluminum, while the typical thickness of evaporated aluminum for light reflectors and chrome decorative coatings is approximately 1000 angstroms. In chamber pretreat and post treat processes aid in the adhesion of the coating.

We have seven automated vacuum chambers both thermal evaporation and magnetron sputtering which include four different sized chambers for a variety of applications and part sizes.

Topcoating Process

When required, a topcoat is applied to enhance, moisture, abrasion, and chemical resistance. We offer many different topcoats for different applications.

Dyed and tinted topcoats are used to create gold, bronze, colored chrome and metallic matte finishes.

Metallic coatings, conductive paints, and functional industrial coatings are all applied in the same area as the base and topcoats utilizing the same equipment.

All work is done in a clean and responsible manner so as to produce the best finish with the least impact on the environment.

Inspection Process

Finished parts are moved to the final inspection and packing area where they are removed from the fixtures and inspected.

Inspection criteria are per each customer’s standard for that individual part and according to their requirements following ISO 9001 — ISO/TS 16949 — AS 9100 guidelines. A custom database is utilized to track process error trends which allow information needed to make constant changes to assure quality.

A tracking tag is included in every box to ensure traceability of parts throughout the entire process.
Parts are then packed for shipment according to customer’s specifications.