part design and prototyping for BMC

Design Considerations for BMCs• Design to optimize inherent properties of material • Use structure as-opposed to mass wherever possible • Keep “Line-of-draw” in mind to minimize reduce o

Reducing the Time to Market for

New BMC Applications

Part Design and Rapid Prototyping for BMC

Part Design Guidelines for BMCs

Design Considerations for BMCs

• Design to optimize inherent properties

of material

• Use structure as-opposed to mass

wherever possible

• Keep “Line-of-draw” in mind to

minimize reduce or eliminate undercuts

and/or trapped steel conditions in mold

• Add molding draft based on line-of

draw to insure minimum wall sections are

maintained

Wall Stock for BMCs

• Maintain nominal wall stock as consistently as possible

•Use structure wherever possible

to increase directional strength and/or combine part features

Wall Stock for BMCs

Wall Stock Recommendations:

• Minimum recommended wall stock 2mm

• Thicker nominal walls required for larger parts with

extended flow lengths

• Wall stock for small parts can be as low as 5mm

• Dependent on part configuration and material selection

Wall Stock for BMCs

Parts with Varying Wall Stock

Parts with significant variances in

wall stock can be successfully molded

in BMC

•Avoid multiple thick-to-thin transitions

•Avoid thin-to thick gate placement

•Minimize or eliminate wall stock variations near dimensionally

critical features

Molding Draft

• Line-of-draw draft angle required on all vertical part surfaces

• Minimum recommended draft 1-degree P/S

• The more draft the better!

• Add draft where possible to small vertical walls

• Linear distance vs angular draft

• Draft vs tolerances ( + draft / - draft)

Draft: Angle or taper added to vertical surfaces on a part

to allow for release from mold during ejection.

Molding Draft

No-draft Requirements

• Can be successfully molded on BMC

• Eliminates secondary machining

• Commonly used for bearing bores &

Undercut Features in BMC Part Designs

• Common in today’s BMC part designs

• Complex shapes not a problem

• Multiple undercuts common

• Tooling technology capable

• Linear or rotary (unscrewing)

• Avoid “trapped steel” conditions

• Consolidate multiple undercuts where

possible into same line-of-draw

Fillet Radii

Blend intersections with fillet radii

wherever possible.

• Increases part strength

• Improves material flow

• Mold construction benefits

• Mold integrity / maintenance benefits

Mounting Hardware for BMCs

BMCs are hardware-friendly

materials that are capable of

accepting a number of common

types of mounting hardware

Mounting Hardware for BMCs

Self-Tapping Screws

• Widely used method of mounting to BMC

• BT-style thread cutting screws

recommended

• Thread-forming screws not recommended

• High torque values

• Excellent torque retention

Mounting Hardware for BMCs

Mounting Boss Sizing for Self-Tapping

Screws

• Wall stock (not boss diameter) to be a

minimum of 1 1/2-times the screw diameter

• Thread engagement to be a minimum of 2 1/2-times the screw

diameter

• Pilot hole to be 002” P/S larger than root-diameter of screw

• Minimal draft in mounting holes

• Blind holes to be 25% deeper than installed screw engagement

Mounting Hardware for BMCs

Rivets

• Commonly used to attach

non-stressed components onto BMC parts

• Used in assembly of household

circuit breaker housings

• Refer to hardware manufacturers recommendations for mounting geometry

Mounting Hardware for BMCs

Insert-Molded & Secondary-Installed Threaded Inserts

Commonly used in BMC applications

where service or installation requires

multiple assembly / disassembly

Snap Features in BMC Part Designs

Given the range of flex modulus achievable in BMCs, snap details are possible provided that they can be

designed with an interference that can operate within the flex-range of the material grade selected

Feel free to contact BMCI’s Technical Group if you have a proposed snap design and would like to review it for

feasibility in BMC

Direct Conversion from Metal Design

• Common in BMC

• Configuration dependent

• May require design modifications to

accommodate molding of features

previously formed by secondary

machining operations

• Significant savings potential associated

with elimination of costly secondary

machining operations

Direct Conversion from Metal Design

• Direct conversion from metal

• Eliminated nine-(9) secondary

machining operations

• Implementing as running change

• Minimal design changes

• Annual volume 600K

• Annual savings : $690K

Vacuum Gearbox Housing

Part Consolidation Through Conversion

Part Consolidation Through Conversion

• Incorporation of multiple part features

into one design

• Part count reduction

• Lower assembly tooling costs

• Reduced assembly labor

• Elimination of secondary machining

operations

• Overall lower assembly cost

Surface Finishes & Appearance Treatments

Rapid Prototyping for BMC Materials

From Art to Part

Rapid Prototyping for BMC Materials

Overview:

The ability to quickly provide customers with prototype parts

in our materials has proven to be both a valuable sales tool,

and an effective method of shrinking product development

lead times Since BMC thermosets do not lend themselves to traditional “Rapid Prototyping” processes such as SLA (Stereo Lithography) of SLS (Selective Laser Sintering), we have

developed our own prototyping process for providing

net-shapes to our customers for evaluation

Rapid Prototyping for BMC Materials

Process:

Our process first involves the pre-molding of plaques, or blocks of the BMC formulation selected for the application These “Billets” of material are then laminated together using epoxy adhesives, or parent resin to form a “Blank” that is roughly the size and shape of the part Lastly, the blank is 3D machined

in our mold shop from the customer part file to produce a net-shape prototype part We have used this process to produce parts as small as a plumbing fitting, and as large as a stove top frame

Rapid Prototyping for BMC Materials

BMCI In-House Tooling /

Prototyping

• Part / product design assistance

• Mold design

• Prototype / production tooling

• Prototype part construction

• Tooling conversion for BMC materials

Rapid Prototyping for BMC Materials

BMCI In-House Tooling /