This document discusses material selection considerations for various components of an electromechanical product. It provides information on different plastic and metal materials, including their properties, grades, finishes and suitability for different applications. Specific material selections are recommended for parts like housing, covers, trays, brackets based on factors like required strength, temperature and flame resistance, cost and manufacturability. Gasket and thermal interface materials are also discussed along with their characteristic properties.

1. Electromechanical Product design
topics

2. Work Experience

3. Plastics

4. Plastics
PET-P For hoist bracket lift
(

5. Plastics
• Surge Arrest Products: PVC Plastic Material. This material is used because it has a natural
Flame Retardant and it is a very heavy feeling and a excellent cosmetic appearance for quality
and the cost of this material normally low. The material is not good in high heat application
above 85 degree C. It also is not good in very low temperature application.
• This unit is made of straight FR PC due to the 5V flame rating requirement (wall mountable
enclosure), and 125 RTI rating requirement (transformer max temps in 45C ambient).
Adesign engineers wanted to select a material with a high impact strength due to the size and
weight of the unit. (2 batteries and transformer heats up)

6. Plastics
Travel Module Rail PC High impact strength Moderate Cost
Low shrink rate No thin wall sections
V-0 Flame Class Low chemical resistance
Good heat resistance
Superior cosmetic surfaces
Translucent
Top Cover ABS High impact strength Moderate Cost
Low shrink rate No thin wall sections
Good heat resistance Low chemical resistance
Superior cosmetic surfaces HB Flame Class
Disk Tray PP Low cost High shrink rate
(Medical High Lubricity HB Flame Class
Grade) High resistance to flexing Poor heat resistance
Excellent for Living hinge
High chemical resistance
Good impact strength
Travel Module Housing PP Low cost High shrink rate
(Medical High Lubricity HB Flame Class
Grade) High resistance to flexing Poor heat resistance
Excellent for Living hinge
High chemical resistance
Good impact strength
Item Description Material Pros Cons
Main Surge Housing PC/ABS High impact strength High Cost
Low shrink rate No thin wall sections
V-0 Flame Class Low chemical resistance
Good heat resistance
Superior cosmetic surfaces
Main Surge Outlet Cover PC/ABS High impact strength High Cost
Low shrink rate No thin wall sections
V-0 Flame Class Low chemical resistance
Good heat resistance
Superior cosmetic surfaces
Secondary Surge Cover PC/ABS High impact strength High Cost
Low shrink rate No thin wall sections
V-0 Flame Class Low chemical resistance
Good heat resistance
Superior cosmetic surfaces
Controller Hook PC High impact strength Moderate Cost
Low shrink rate No thin wall sections
V-0 Flame Class Low chemical resistance
Good heat resistance
Superior cosmetic surfaces
Translucent
Label Accent Strip PC High impact strength Moderate Cost
Low shrink rate No thin wall sections
V-0 Flame Class Low chemical resistance
Good heat resistance
Superior cosmetic surfaces
Translucent
Button Guard PC High impact strength Moderate Cost
Low shrink rate No thin wall sections
V-0 Flame Class Low chemical resistance
Good heat resistance
Superior cosmetic surfaces
Translucent
6

7. Plastics

8. Plastics

9. Gaskets
•GASKET MATERIAL : SILICON
RUBBER, MOMENTIVE SILPLUS 40
MP
• HARDNESS : 40 SHORE A

10. Gaskets
• Key Selection Considerations for Gasket Materials
• When choosing a gasket material, there are several factors to keep in mind to
ensure the one chosen is appropriate for the intended application. Some of
the key considerations are:
• Temperature: what temperature range is it expected to withstand?
• Pressure: what pressure range is it expected to withstand?
• Media: what materials will it be exposed to? (e.g., are the process fluids abrasive
or corrosive?)
• UV and ozone exposure: will it be exposed to UV radiation and ozone?
• Product standards: is it subject to any industry-specific product requirements?
(e.g., does it need EMI shielding properties?)
• Industry standards: is it subject to any other industry-specific standards? (e.g.,
does it need to meet ASTM, UL, or Mil-spec requirements?)

11. • Compression Set
– Compression Set is defined as the decrease in thickness of a rubber
which has been deformed under specific conditions of load, time and
temperature. Normally shown as a percentage. Generally tested to
ASTM D395 Method B. Generally a lower percentage of Compression
Set indicates a better quality of Material.
• A good quality Solid Rubber would have a Compression Set below
20%, most Sheet Rubber will have a Compression Set around 30%,
poor quality, under cured, or badly mixed Rubber Sheeting will
exhibit a Compression set of 45% or more.

14. SEMI-ALUMINIUM
Part MATERIAL AND
GRADE
FINISIH Operating
conditions
Chamber AL-6061 t6
Al Anodise
TOP PLATE AL 6061-T651
INTERNAL BRACKET ALUMINIUM
SHEETMETAL 5052
H32
Commonly reffred Alodine or Iridit
CHEMICAL FILM PER MIL dtl 5541,class 1a TYPE II.
Class 3-clear color when low electrical resistance required (Enclosure, brackets)
Class 1A,color gold , max corrosion resistance
Brass Silver plate
PED LIFT-DIE CAST ALUMINIUM ANSI
356.0-T51
STANDARD-ANSI 91000

15. CRS
Part MATERIAL AND
GRADE
FINISIH Other
ENCLOSURE Carbon steel Zn plate with color<>, chromate per ASTM B633 TYPE<>
<SERVICE CONDITON>
Color : Yellow or clear
Type-2, SC-3: yellow chromate
Type-3: SC-2: Low electrical resistance
Caster bracket Steel 8620
60ksi, 20%
elongation
Zinc chromate clear, type 3,sc 2 150 micro inch
Enclosure, mtg bracket
inverter
GI 275 GSM CHROME
FREE, 2.0mm
Polyseter powed coat 70u thk

16. SEMI-SS
Part MATERIAL AND
GRADE
FINISIH Operating conditions
Gas lines/fore lines
gas delivery system
SS 316 L Electropolish
MACHINED PART SST
SHEETMETAL SST Passivation ASTM A -967, NITRIC ACID PASSIVATION WITH NITRIC 2 OR 3 DEPENDS
ON GRADE

17. COPER
Busbar Copper UNS C11000 Electroless ni plating 20u,ISO1456
Nickle plating 2U
and prior tin plating
10U
Astm b 545
Icp electrode Copper OFHC-
C10100
No finish
C10100 OFHC Copper is produced by the direct conversion of selected refined cathodes and castings under carefully
controlled conditions to prevent contamination of the pure oxygen-free metal during processing. The method of producing
OFHC copper ensures extra high grade of metal with a copper content of 99.99%. With so small a content of extraneous
elements, the inherent properties of elemental copper are brought forth to a high degree.
Characteristics of OFHC copper are:
High Ductility
High Electrical & Thermal Conductivity
High Impact Strength
Good Creep Resistance
Ease of Welding
Low Relative Volatility under high vacuum

18. Plastics machined
Pcw block ACETAL/ WITH
NITRONIC HELICOIL
INSERT

19. Lables
• Safety lable
• .002”-.003 White Mylar backing with 3M467
• Laminate .001-.002” clear matte
• Text size 8 point bold text
• Ansi z535.1 amd z535.4
• Suitable use on steel, aluminium, painted and
plastic surface

20. TIM
• Thermal interface material
• From Wikipedia, the free encyclopedia
• Jump to navigationJump to searchA thermal interface material (shortened to TIM[1]) is any material that is inserted between two components in order to enhance the thermal coupling
between them. A common use is heat dissipation, in which the TIM is inserted between a heat-producing device (e.g. an integrated circuit) and a heat-dissipating device (e.g. a heat sink).
At each interface, a thermal boundary resistance exists to impede heat dissipation. In addition, the electronic performance and device lifetime can degrade dramatically under continuous
overheating and large thermal stress at the interfaces. Therefore, for the last several decades, there have been intensive efforts in developing various TIMs with the aim of minimizing the
thermal boundary resistance between layers and enhancing thermal management performance, as well as tackling application requirements such as low thermal stress between
materials of different thermal expansion coefficients, low elastic modulus or viscosity, flexibility, and reusability:[2]
• Thermal paste: Mostly used in the electronics industry, it provides a very thin bond line and therefore a very small thermal resistance. It has no mechanical strength (other than the
surface tension of the paste and the resulting adhesive effect) and will need an external mechanical fixation mechanism. Because it does not cure, it is used only where the material can
be contained or in thin application where the viscosity of the paste will allow it to stay in position during use.
• Thermal adhesive: As with the thermal paste, it provides a very thin bond line, but provides some additional mechanical strength to the bond after curing. Thermal glue allows thicker
bond line than the thermal paste, as it cures.
• Thermal gap filler: This could be described as "curing thermal paste" or "non-adhesive thermal glue". It provides thicker bond lines than the thermal paste as it cures while still allowing
an easy disassembly thanks to limited adhesiveness.
• Thermally conductive pad: As opposed to previous TIM, a thermal pad comes not in liquid or paste form, but in a solid state (albeit often soft). Mostly made of silicone or silicone-like
material, it has the advantage of being easy to apply. It provides thicker bond lines, but will usually need higher force to press the heat sink onto the heat source so that the thermal pad
conforms to the bonded surfaces.
• Thermal tape: This adheres to the bonded surfaces, requires no curing time and is easy to apply. It is essentially a thermal pad with adhesive properties.
• Phase-change materials (PCM): Naturally sticky materials, used in place of thermal pastes. Its application is similar to solid pads. After achieving a melting point of 55–60 degrees, it
changes to a half-liquid status and fills all gaps between the heat source and the heat sink.
• Metal thermal interface materials (metal TIMs): Metallic materials offer substantially higher thermal conductivity as well as the lowest thermal interface resistance. This high conductivity
translates to less sensitivity to bondline thicknesses and coplanarity issues than polymeric TIMs.[3]

21. Fan selection

22. IP

23. IEC verus NEMA

24. NEMA

25. FR –flammability rating
•UL 94-5VA Surface Burn; Burning stops within 60 seconds,
test specimens MAY NOT have a burn-through (no hole). This
is the highest (most flame retardant) UL94 rating.
•UL 94-5VB Surface Burn; Burning stop within 60 seconds, test
specimens MAY HAVE a burn-through (A hole may be present)
•UL 94 V-0 Vertical Burn; Burning stops within 10 seconds, NO
flaming drips are allowed
•UL 94 V-1 Vertical Burn; Burning stops within 60 seconds, NO
flaming drips are allowed
•UL 94 V-2 Vertical Burn; Burning stops within 60 seconds,
Flaming drips ARE allowed.
•UL 94 H-B Horizontal Burn; Slow horizontal burn test (H-B)
are considered "self-extinguishing". The lowest (least flame
retardant) UL94 rating.

26. FR Flammability Rating
•The results of most UL 94 flammability tests are not applicable to materials whose thickness exceeds 13.0 mm,
or whose surface area exceeds 1m2.
•The UL rating should be reported along with the material thickness and color, and reporting only the UL rating
without thickness and color is not feasible.
•Effects of Flammability
Colorant/Additives: For best results, stick with a base resin with no additives as most additives may not carry a UL
rating. If a specific additive is required, you would likely need to work with a compounder that could custom
create a flame-retardant blend of the base resin, like color matching, for example.
•Part Thickness: UL ratings are measured at various thicknesses and this can drastically change your part’s UL
rating. If you were looking for a UL 94 V-0 material for a part with thin or thick walls, as shown in the chart below,
your part may fail — so pay close attention to wall thickness and material selection

27. Flammability Rating
Flammability test video of
plastic material

28. Plastic properties
https://plastics.ulprospector.com/properties/

29. UL 746
UL_746: Plastic Material Properties
1
Comparative Tracking Index (CTI) UL 746
2
High Amp Arc Ignition (HAI) UL 746
3
High Voltage Arc Resistance to Ignition (HVAR) UL 746
4
High Voltage Arc Tracking Rate (HVTR) UL 746
5
Hot-wire Ignition (HWI) UL 746
6
Outdoor Suitability UL 746C
7
Relative Temperature Index (RTI) Electric UL 746
8
Relative Temperature Index (RTI) Mechanical with Impact UL 746
9
Relative Temperature Index (RTI) Mechanical without Impact UL 746

30. Comparative Tracking Index (CTI)
• The Comparative Tracking Index (CTI) is used to measure the electrical breakdown (tracking) properties of an insulating
material.
• A large voltage difference gradually creates a conductive leakage path across the surface of the material by forming
a carbonized track.
• Testing method is specified in IEC standard 60112 and ASTM D3638.
• Tracking is an electrical breakdown on the surface of an insulating material wherein an initial exposure to electrical arcing
heat carbonizes the material. The carbonized areas are more conductive than the pristine insulator, increasing current flow,
resulting in increased heat generation, and eventually the insulation becomes completely conductive.
• To measure the tracking, 50 drops of 0.1% ammonium chloride solution are dropped on the material, and the voltage
measured for a 3 mm thickness is considered representative of the material performance. Also term PTI (Proof Tracking
Index) is used: it means voltage at which during testing on five samples the samples pass the test with no failures.
• Tracking is defined as the formation of conductive paths due to electrical stress, humidity, and contamination.
• The CTI test provides an accelerated simulation of conditions of surface discharges and possible resulting tracking and failure
(typically a “short”) in equipment using insulating materials. This test also provides a means to compare insulating materials
performances under wet and contaminated conditions.
• Depending on the CTI of the insulating material used, the minimum creep age distance required will vary. The higher the CTI
value, the lower the minimum creep age distance required.
• In practice, the higher the CTI of the insulating material used, the closer two conductive parts can be. The result is often a
smaller part, increasingly desirable in technology and industry today. These values would be of particular interest to design
engineers who must comply with UL requirements.

31. Comparative Tracking Index (CTI)
CTI Testing UL
Test specimen ≥20 mm x ≥20 mm x ≥3 mm
Test voltage Between 100 V and 600 V (50 Hz) in 25 V
steps
IEC Test solution 395 Ωcm
Drop volume 20 mm³
Failure criteria Current on breaking ≥0,5 A >2,0 s or
material burns

32. HOT wire ignition test
HWI video

33. HOT wire ignition test
HWI video

36. Relative Temperature Index (RTI) - UL 746
https://www.ul.com/resources/evaluation-elevated-temperature-
performance-plastics-south-asia

39. Heat deflection temperature
• ASTM D648:
The deflection temperature is the temperature at which
a test bar, loaded to the specified bending stress, deflects
by 0.010 inch (0.25 mm).
• Scope:
Heat deflection temperature is defined as the
temperature at which a standard test bar deflects a
specified distance under a load.
• It is used to determine short-term heat resistance. It
distinguishes between materials that are able to sustain
light loads at high temperatures and those that lose
rigidity over a narrow temperature range.
ASTM D648: TEST SETUP

41. reliability