Rubber Molding Math

1
Rubber Molding Math

• RR Rubber Molding, Inc.
• By Rick Norman, President Owner
• Sixto Castillo III, Vice President of Operations
• Carmen Castillo, Quality Control Specialist
• April 23, 2007
• Rialto High School Algebra I Classes

2
Introduction

• Background
• Personal background
• Company background
• Interesting facts
• The mold process

3
Material Prep
4
Insert Prep
5
Mold Retrieval
6
Mold Loading
7
Closing the Press
8
Finishing
9
Inspection
10
Math in the field

• Accounting (Business Math)
• Cost/Volume/Weight/Density
• Mechanical/Scale Drawings
• Dimension checks

11
O-ring Facts

• The material used to create an O-ring is sold by
  weight.
• To determine the cost of material for making an
  O-ring the actual weight of the material must be
  determined.
• Determining the actual weight can be done in two
  (2) parts
• Part 1We use information from the drawing to
  find the volume and density.
• (The density, or specific gravity, is given on
  the Rheometer Test Report that comes with each
  batch of material thats purchased.)
• Part 2Then we use the volume and density to
  calculate the weight.

12
O-ring Facts Cont

• To determine the actual weight (load weight) we
  use 2 formulas

13
O-ring Problem

• Determine the weight of the material for making
  an O-ring with the following dimensions and
  density (specific weight).
• Diameter (D) 15 ft
• Cross section (d) 2 ft
• Density 1.5 lbs/ft
• Remember

14
O-ring Problem Part 1

• D 15 ft
• d 2 ft

We leave the answer in terms of Pi so we dont
lose significant values.
Now lets look at the Specific Weight (aka
Density).
15
O-ring Problem Part 2

• Find the Weight (aka Load Weight) using the
  density formula.
• Density 1.5 lbs/ft3
• Volume 15p2 ft3

We need approximately 222.066 lbs of raw material
to create just one (1) of the described O-ring.
16
O-ring Problem 2

• Determine the weight of the material for making
  an O-ring with the following dimensions and
  density (specific weight).
• Diameter (D) 20 ft
• Cross section (d) 1 ft
• Density 1.2 lbs/ft
• Remember

17
O-ring Problem 2 Part 1

• D 20 ft
• d 1 ft

We leave the answer in terms of Pi so we dont
lose significant values.
Now lets look at the Specific Weight (aka
Density).
18
O-ring Problem 2 Part 2

• Find the Weight (aka Load Weight) using the
  density formula.
• Density 1.2 lbs/ft3
• Volume 5p2 ft3

We need approximately 59.2176 lbs of raw material
to create just one (1) of the described O-ring.
19
Hands-on Activity

• Break up into 5 groups
• Calculate the volume of your groups piece of raw
  material
• How much does your groups piece of raw material
  weight?
• Using the volume and weight calculate the density
  of your groups piece of raw material.
• Use
• 1,728 in3 1 ft3
• Compare the density you calculated with its
  rheometer test report.
• O-ring check
• Sample O-rings
• Tools
• Pi Tape
• Go/No go-gauge

20
Thank You

• Questions?
• Final thoughts
• Comments