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Injection Molding Reference Guide
8 Units and Conversions
Metric is the most common form of measurement used worldwide and is based on a system of tenths. For example, the Meter is the metric standard for length and one tenth of a meter is a decimeter. One hundredth of a meter is a centimeter, one thousandth of a meter is a millimeter and one thousand meters is a kilometer. The same convention applies to most metric standards: For example, the Gram, Decigram, Centigram, Milligram, and the Liter, Deciliter, Centiliter, and Milliliter.
The imperial system is an older system of measurement that does not use standard conventions. Imperial units include inches, feet, pounds, ounces and gallons. Imperial units are very common in the United States and North America, but less common globally. In the injection molding industry, the inch is the most commonly used imperial unit of measurement for length. Twelve inches equal a foot, three feet equal a yard, and one thousand, seven hundred sixty yards equals a mile.
Imperial units can also become somewhat confusing when deal-ing with weight and volume measurements. For example, sixteen ounces in weight equals one pound, while one hundred twenty-eight fluid ounces equals a gallon. Since most injection molding facilities operate globally, it is common for personnel to convert measure-ments from metric units to imperial units, and vice versa, on a regular basis.
8.1 Time
Figure 8a: Common Time Units
Abbr. |
Unit |
s |
Second |
min |
Minute |
hr |
Hour |
Figure 8b: Common Time Conversions
Equals |
|
1 min |
60 s |
1 hr |
60 min |
8.2 Rotation
Figure 8c: Common Rotation Units and Terms
Abbr. |
Unit / Term |
CW |
Clockwise |
CCW |
Counterclockwise |
Rev |
Revolution (may be notated as decimal or fraction) |
° |
Degree |
rad |
Radian |
Figure 8d: Common Rotation Conversions
Equals |
|
1 Rev |
360° |
½ Rev |
180° |
¼ Rev |
90° |
1° |
0.01745 rad |
1 rad |
57.2957° |
8.3 Temperature
Figure 8e: Common Temperature Units & References
Standard |
Abbr. |
Unit |
Water Freezes |
Water Boils |
Metric |
°C |
Degrees Celsius |
0°C |
100°C |
Imperial |
°F |
Degrees Fahrenheit |
32°F |
212°F |
Figure 8f: Common Temperature Conversions
Equation |
|
°F to °C |
(°F – 32) ÷ 1.8 |
°C to °F |
(°C * 1.8) + 32 |
8.4 Length
Figure 8g: Common Length Units
Standard |
Abbr. |
Unit |
|
Metric |
mm |
Millimeters |
|
cm |
Centimeters |
||
m |
Meters |
||
Imperial |
in |
” |
Inches |
ft |
’ |
Feet |
Figure 8h: Common Length Conversions
Convert From: |
To: |
Multiply By: |
mm |
cm |
10 |
cm |
m |
100 |
cm |
mm |
0.1 |
ft |
in |
12 |
in |
ft |
.0833 |
in |
cm |
2.54 |
in |
mm |
25.4 |
mm |
in |
.03937 |
cm |
in |
.3937 |
8.5 Speed
Figure 8i: Common Speed Units
Standard |
Abbr. |
Unit |
Metric |
mm/s |
Millimeters per second |
cm/s |
Centimeters per second |
|
Imperial |
in/s |
Inches per second |
ft/s |
Feet per second |
Figure 8j: Common Speed Conversions
Convert From: |
To: |
Multiply By: |
mm/s |
in/s |
.03937 |
cm/s |
in/s |
.3937 |
in/s |
mm/s |
25.4 |
in/s |
cm/s |
2.54 |
8.6 Area
Figure 8k: Common Area Units
Standard |
Abbr. |
Unit |
Metric |
mm² |
Square Millimeters |
cm² |
Square Centimeters |
|
m² |
Square Meters |
|
Imperial |
in² |
Square Inches |
ft² |
Square feet |
Figure 8l: Common Area Conversions
Convert From: |
To: |
Multiply By: |
mm² |
cm² |
.01 |
cm² |
mm² |
100 |
mm² |
in² |
0.00155 |
in² |
mm² |
645.146 |
8.7 Volume
Figure 8m: Common Volume Units
Standard |
Abbr. |
Unit |
Metric |
mm³ |
Cubic Millimeters |
cm³ |
Cubic Centimeters |
|
m³ |
Cubic Meters |
|
l |
Liters |
|
ml |
Milliliters |
|
Imperial |
in³ |
Cubic Inches |
ft³ |
Cubic Feet |
|
fl oz |
Fluid Ounces |
|
gal |
Gallons |
Figure 8n: Common Volume Conversions
Convert From: |
To: |
Multiply By: |
mm³ |
cm³ |
0.001 |
cm³ |
mm³ |
1000 |
cm³ |
in³ |
0.061 |
in³ |
cm³ |
16.387 |
l |
gal |
0.264 |
gal |
l |
3.785 |
ml |
fl oz |
0.0338 |
fl oz |
ml |
29.57 |
8.8 Volumetric Flow Rate
Figure 8o: Common Flow Rate Units
Standard |
Abbr. |
Unit |
Metric |
mm³/s |
Cubic Millimeters per Second |
cm³/s |
Cubic Centimeters per Second |
|
lpm |
Liters per Minute |
|
Imperial |
in³/s |
Cubic Inches per Second |
gpm |
Gallons per Minute |
Figure 8p: Common Volumetric Flow Rate Conversions
Convert From: |
To: |
Multiply By: |
mm³/s |
cm³/s |
0.001 |
cm³/s |
mm³/s |
1000 |
cm³/s |
in³/s |
0.061 |
in³/s |
cm³/s |
16.387 |
lpm |
gpm |
0.264 |
gpm |
lpm |
3.785 |
8.9 Mass
Figure 8q: Common Mass Units
Standard |
Abbr. |
Unit |
Metric |
mg |
Milligrams |
g |
Grams |
|
kg |
Kilograms |
|
Imperial |
oz |
Ounce |
lb |
Pound |
Figure 8r: Common Mass and Force Conversions
Convert From: |
To: |
Multiply By: |
g |
mg |
1000 |
g |
kg |
0.001 |
mg |
g |
0.001 |
kg |
g |
1000 |
lb |
oz |
16 |
oz |
lb |
0.0625 |
g |
oz |
0.03527 |
oz |
g |
28.35 |
kg |
lb |
2.2046 |
lb |
kg |
0.4536 |
8.10 Mass Flow Rate
Figure 8s: Common Mass Flow Rate Units
Standard |
Abbr. |
Unit |
Metric |
g/hr |
Grams per Hour |
kg/hr |
Kilograms per Hour |
|
Imperial |
oz/hr |
Ounces per Hour |
lb/hr |
Pounds per Hour |
Figure 8t: Common Mass Flow Rate Conversions
Convert From: |
To: |
Multiply By: |
g/hr |
kg/hr |
0.001 |
kg/hr |
g/hr |
1000 |
lb/hr |
oz/hr |
16 |
oz/hr |
lb/hr |
0.0625 |
g/hr |
oz/hr |
0.03527 |
oz/hr |
g/hr |
28.35 |
kg/hr |
lb/hr |
2.2046 |
lb/hr |
kg/hr |
0.4536 |
8.11 Pressure
Figure 8u: Common Pressure Units
Standard |
Abbr. |
Unit |
Metric |
bar |
Bar |
MPa |
Megapascal |
|
Imperial |
psi |
Pounds per Square Inch |
Figure 8v: Common Pressure Conversions
Convert From: |
To: |
Multiply By: |
bar |
MPa |
0.1 |
MPa |
bar |
10 |
bar |
psi |
14.504 |
psi |
bar |
0.06895 |
MPa |
psi |
145.04 |
psi |
MPa |
0.006895 |
8.12 Tonnage
Figure 8w: Common Tonnage Conversions
Convert From: |
To: |
Multiply By: |
US ton |
metric ton |
1.1023 |
metric ton |
US ton |
0.9097 |
US ton |
lb |
2000 |
lb |
US ton |
0.0005 |
metric ton |
kg |
1000 |
kg |
metric ton |
0.0010 |
8.13 Common Conversion Tables
Figure 8x: Celsius to Fahrenheit (°C to °F)
Figure 8y: Millimeters to Inches (mm to in)
Figure 8z: bar to psi
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Injection Molding Guide
Table of Contents
- Part 1 - Understanding Plastics
- Part 2 - Plastics Materials Overview
- Part 3 - Properties, Additives, & Preparation
- Part 4 - Establishing a Scientific Molding Process
- Part 5 - Seven Steps to Scientific Troubleshooting
- Part 6 - Defects
- Part 7 - Basic Mold & Part Design Guidelines
- Part 8 - Units and Conversions
- Part 9 - Frequently Used Calculations
- Part 10 - The Importance of Training
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