Category Archive: Electronic Equipment Rack Features

How to Choose the Right Finishing Options for your Custom Rack

Just like electronic equipment rack designs and accessories, the end use for your product determines the best type of finish to use for your custom rack. Finishes provide a durable coating that protects a product from its environment and function best. Does your enclosure need to be able to withstand high temperatures? Avoid corrosion? Promote electrical conductivity?

Frankly, cost and production time are less important factors. You want the best results possible! Read on to determine which finishing option is best for your custom rack.

Bare Metal Finishes

There are three options: “no finish”, “grained finish” and “tumbled”.

About “No Finish/Natural”

Parts are de-burred with no additional finishing, but minor surface scratches and blemishes are to be expected. There’s no additional cost and best used for functional parts that won’t be on display.

About “Grained Finish”

Parts are de-burred, and then given a specific linear grain direction via brushing. It can only be applied to accessible flat exterior faces on machined parts and can also be digitally printed or silkscreened.

About “Tumbled Finish”

A great option for machined parts, but maximum size is 10x10x10. This process smooths and imparts non-directional finish via tumbling in abrasive medium. It can also be digitally printed or silkscreened.

Powder Coating

Powder coating is a dry finishing process in which free-flowing, thermoplastic or thermoset powder material, rather than a liquid suspension, is applied to a surface, melted, and then allowed to dry and harden into a protective coating. It provides a better, more durable finish than paint. It’s also highly effective in removing surface defects.

Advantages:

  • Durability
  • Thicker and specialty finishes available
  • Less environmental impact
  • Shorter curing, processing and drying times
  • Undamaged and uncontaminated powder overspray can be reclaimed and recycled for future applications (utilization rate is close to 100%)

Disadvantages:

  • Range of suitable materials is limited due to the fact that it must be heated to be cured
  • Difficultly producing thin coatings
  • Not cost-effective for custom, small batch coating needs
  • Curing and drying times increase for large, heavier parts (due to higher temperatures required)

Chemical Conversion Coating

Also known as Chem Film or chromate coating, this process applies chromate to a metal surface that is corrosion resistant, durable and exhibits stable electrical conductivity.

If you’re using your rack in a rugged environment, use a vendor that is MIL-DTL-5541F qualified. The standards include utilizing a process that doesn’t use toxic hexavalent chrome and has been replaced with the safer zirconium, titanium or trivalent chromium. It’s also been sufficiently tested against corrosion and proves to have reliable electrical conductivity.

Advantages:

  • Extends the service life of parts
  • Cost efficient and economical
  • Doesn’t change part dimensions

Disadvantages:

  • High energy demand

Anodizing

Anodizing is an electrochemical process that involves dipping aluminum into a bath of acid and passing an electric current through the medium. It converts the surface into a decorative, durable, corrosion-resistant oxide finish.

Anodized aluminum protects satellites from the harsh environment of space, and revolutionized the construction of computer hardware, scientific instruments and consumer products like kitchen appliances.

Advantages:

  • Durability – creates an extremely hard surface that is more resistant to scratches
  • Resistant to corrosion, heat and electricity
  • Low environmental impact – non-toxic finish with no harmful by-products

Disadvantages:

  • Limited color selection and its often subject to color variations
  • Requires a high-grade alloy of aluminum
  • Not cost effective for small quantities

Contact us today to learn more about the different types and colors of enclosures finishes that are available.

Protecting Electronic Devices from Vibration & Shock

Vibration is bad for electronics. It can damage the boards and components potentially causing permanent failure. But a well-engineered enclosure protects delicate equipment from vibration damage by isolating it from external sources. Utilizing a stabilizer kit for your rack can add an additional layer of security.

These vital electronics are subjected to stressors in a wide spectrum of applications ranging from in-office or industrial power stations to ruggedized, aerospace systems or other military deployment. Even if intended for more mild environments, nearly all electronics are subject to some level of vibration during their lifecycle. Typical shock values for industrial use might be in the 5G to 10G range whereas systems on naval ships need to withstand shocks in excess of 20G.

Types of shock and vibration

If your equipment is mounted on a ground-based or airborne vehicle, shipboard mounted or needs to withstand natural weather patterns and seismic events, ruggedized construction should be one of the, if not THE, primary design criteria.

There are two types of vibration: random or sinusoidal. Random is a varying waveform similar to riding in a vehicle rolling across rough terrain. Sinusoidal vibration occurs at distinct frequencies and is continuous, like that of a rotating engine on a helicopter.

Stress testing can uncover defects in a design before they become expensive problems. And often times, the only way to verify that a rack and its isolation mounts will provide sufficient protection is through instrumented testing. Our A&J electronic equipment racks have been designed and tested to meet MIL standards:

  • MIL-STD 810F — environmental shock and vibration
  • MIL-STD-167 — shipboard vibration
  • MIL-STD-901D — high impact and shock testing for Navy shipboard machinery and equipment

Rack Type

Test

Rack Height (in)

Model

Test Results

Light Duty

Shock

72

9264-1000-1

MIL-S-901C
Total weight 1211 lbs.
Hard mounted

Light Duty

Shock and Vibration

72

9096-109

MIL-S-901C Blows
Total weight 845 lbs.
Hard mounted

Medium Duty

Shock and Vibration

76

9260-1000

MIL-STD-810, method 516
Isolation system installed
Vibration to 33 Hz

Medium Duty

Shock

72 H, 30 D

9399-1000

MIL-S-901C
Total weight 638 lbs.
Vibration to 33 Hz

Medium Duty

Shock

60

60-D1-1001

MIL-S-901C 9
Total weight 1254 lbs.
Hard mounted

Medium Duty

Shock and Vibration

68.68

9216-1000

MIL-S-901C 9 Blows
Total weight 1254 lbs.
Isolation system installed

Medium Duty

Shock and Vibration

72

9194-100

MIL-S-901C 12 Blows
Total weight 998 lbs.
Hard mounted
Vibration to 33 Hz

Medium Duty

Shock and Vibration

59

9153-1000

MIL-S-901C 9 Blows
Total weight 865 lbs.
Hard mounted
Simulated weight

Medium Duty

Shock and vibration

72

72-D1-1001

MIL-S-901C 9 Blows
Two racks joined at the top
Total weight 1262 lbs.
Hard mounted

Medium Duty

Shock and vibration

40

9149-100

MIL-S-901C 6 Blows
Total weight 450 lbs.
High temp & humidity

Medium Duty

Shock and vibration

72 H, 36 D, 36 W

9423-1001

MIL-S-901C 9 Blows
Total weight 695 lbs.
Internal isolation systems

Medium Duty

Shock

60

60-D1-1001

MIL-S-901C 9 Blows
Total weight 650 lbs.
Hard mounted

Heavy Duty

Shock and Vibration

76

76-G1-1001

MIL-S-901C Blows
Total weight 922 lbs.
Free standing

Heavy Duty

Shock and vibration

72

9143-100 TG-2

MIL-S-901C 9 Blows
Total weight 928 lbs.
Hard mounted
Simulated weight

Key rack components to protect against shock & vibration

Isolators

The main goal in handling shock and vibration is to isolate the equipment from excitement by reducing the amplitude and frequency of waves. Enter: isolators. They’re critical! And act as a highly stable buffer between the source of the vibration and the object or surface. A good system has two main components, a spring to support the load and a damping element to dissipate the energy.

Two common types of vibration isolators are used in rack configurations: 

  • Wire Rope Coils – the ideal solution for providing low frequency, highly damped vibration isolation and excellent shock attenuation. They often require little maintenance, are made from durable metals and keep functioning under varying temperatures in corrosive environments. 
  • Seismic Mounts – whether you’re in a seismic region of the country or on a Naval ship, these mounts are designed to provide the strength and isolation necessary to control the motion of equipment

Varying the size, shape, construction material and number of coils all affect the spring rate and damping, as well as mounting placement. 

Common applications for vibration and shock isolators include avionics and equipment, computer equipment and disc drivers, control panels, electrical transformers, fans and blowers, industrial machinery, marine and shipboard equipment, medical equipment, power plants and cooling towers, pumps and centrifuges, and compressors. 

Rack Frame

Obviously the rack’s exterior frame should be rigid construction to withstand any buckling. At A&J, we developed a unique bolted-together design that lends structural integrity, eliminating the need for welding. The modular design allows a wide range of sizes and configurations to be incorporated. For seismic zones or rugged applications, a back stiffener or X-brace can be added near the top, middle and bottom to protect from movement. Another option to consider is double-walled construction where the frame has two layers of sheet metal for extra strength. 

 Contact us for more detail on a particular enclosure design feature or schedule a chat with one of our engineers

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