Project: Soap Dish

Narrative: You are on a product design team responsible for designing a tray for a bar of soap that will prevent the soap from dissolving from excessive water contact. This will require the soap cavity to have several raised features to elevate the bar of soap above the bottom of the cavity. Draft angles must be applied to interior and exterior vertical surfaces and be in the range of 8 - 10 degrees. The shelled version of the soap dish must have a wall thickness of .100”, with the bottom face of the design excluded from the shell operation so as to remain open. The shelling function allows the design of objects with thinner walls, resulting in material savings. This is a critical issue in the design of injection molds for industrial production applications.

Your team should brainstorm, discuss and then produce a four-view conceptualization sketch that must be attached to the printed multi-view drawings produced with solid modeling software. Include the required calculations on the drawings. A prototype of the solid bottom soap dish design will be produced on a CNC vertical milling machine.

Concepts:

Extrude, Fillet, Chamfer, Draft Angle, Mass Properties, Creating CNC code, Fixturing Stock, Robotic Parts handling, Milling Machine Setup, Part Production

Geometric Requirements:  If you have saved your soap dish solid model from Introduction to Engineering Design, it can be modified following the parameters given below. If you do not have the solid model on disk, then follow the parameters below.  The inside cavity must be 0.650 deep and be able to accommodate a bar of soap 2.500 wide x 4.250 long.  The outside dimensions must be 1.000” x 3.000” x 5.000”.  The outside shape does not have to evolve from a rectangular solid; try using other shapes that will fit in an area not to exceed 24.750 square inches.  Use the EXTRUDE-cut option to produce the top inside cavity.  The fillet radius for all inside corners is to be 0.250”.  The fillet radius for all outside edges except the bottom, as well as the top inside edge is to be 0.125”.

Project Lead The Way® Copyright 2006 CIM – Activities – Project: Soap Dish – Page 1  The bottom edge is not to be filleted.  The area immediately under the soap must have several raised features made up of narrow ridges or lettering to allow the soap to dry out between uses.  Prepare the standard four-view drawing with the appropriate dimensions. Print on 18 x 24 paper.

Inquiry:

Solve the following using the mass property function and the appropriate calculations.

A. Find the volume and mass of polyethylene necessary to manufacture 1000 soap dishes if the design has a bottom surface that has been shelled using a thickness of .100”.

B. What will be the cost of the polyethylene required to manufacture 1000 shelled soap dishes?

C. Find the volume and mass of polyethylene necessary to manufacture 1000 soap dishes if the design has a solid bottom surface with no shell applied.

D. What will be the cost of the polyethylene required to manufacture 1000 soap dishes with solid bottoms?

E. What is the cost savings of manufacturing the shelled soap dish instead of the solid bottom soap dish?

Other Applications: What other consumer products would make use of the shell feature to help produce a product design that uses less material, while still providing adequate strength to enable it to perform its intended task?

Evaluation: How closely does the design adhere to the Geometric Requirements?

Supplemental Information:

 The density of the high-density polyethylene is 0.034 lbs. per cubic inch.  The price per pound of the high-density polyethylene is $2.25