Arrowhead - Custom Fiberglass Project Development

Most people have heard about fiberglass products and maybe even have researched enough to know that fiberglass can provide weight reduction over other products like metals, concrete and even wooden products, but they don't understand the process required to get their project produced. Below we will try to explain the basic steps required from start to finish with a fiberglass product.

Fiberglass Project Review and Production Process

Design Review

Requirements

Pattern

Molds

Parts

Review the Fiberglass Project Design

Each new product that Arrowhead works with requires a review of the current design and the products requirements. This review process allows us to determine the manufacturability of the product and also offer suggestions to our customers that may make the product more economical and effectively.

Is the current design manufacturable with fiberglass processes?

Size - The size of the finished part is discussed
Draft Angles - 3° or greater is preferred
Radii - Sharp corners can hinder manufacturability
Wall Thickness - The thickness of the finished part is determined
Die locks - Does your part contain features that will require multi-piece molds?

What type of finish is required for the product?

Uncoated exposed resin/ glass molded surface
Sandable gelcoat surface for customer painting
Finished gelcoat industrial quality
Finished gelcoat Class A automotive finish
Post-molded painted finish

What type of fiberglass matrix and resin will be required?

Determine the type of resin required for project
- General Purpose
- Chemical Resistance
- Fire Retardant
- Heat Stability
- Impact Resistance
- UV Stability
Determine the fiberglass requirements
- Glass to resin Ratio (usually 30% glass : 70% resin)
- Fiber weave - chop strand, woven mat and bi-directional mat
- Fiber makeup - Standard E glass, arymid fiber, carbon fiber
Finished gelcoat industrial quality
Finished gelcoat Class A automotive finish
Post-molded painted finish

Are secondary fabrication processes required?

Inserts and reinforcements

Stiffening Materials - Core mats, foam cores, balsa cores, ridged wooden cores, metal plates, engineered extrusions
Brackets - Hinges, threaded inserts, latches, mounts, bumpers

What type of "B" surface requirements are there?

Rough open glass/ resin surface (burr free)
Pigmented Resin
Hot Coated Fiberglass
Smooth Smooth Finish (Requires RTM Process)

Determine Fiberglass Molding Requirements

After the project design has been reviewed and the product designs are finalized Arrowhead will work with you to determine the types of molds, fixtures and patterns that will be required for production of your project.

What type of "B" Surface requirements were determined?

Rough Backside
- One-off fabricated part
- Open molded fiberglass part, typical volume 250 part per year per mold
Smooth Backside
- RTM Lite (light weight composite molds) typical volume 2000 parts per year per mold
- Conventional RTM (machine matched metal molds) typical volume 2750 parts per year per mold
- CCBM molding (smooth but porous surface machined metal molds) typical volume 6000 parts per year per mold
- Cold Molded (smooth but porous surface machined metal molds) typical volume 6000 part per year per mold
- SMC - typical volume 12000 parts per year per mold

What type of geometry does the part consist of?

No die locks single cavity mold works with any above listed molding method
Die Locked

Open molded with parting flanges
CCBM with minor die locks
Other molding methods but may require experimenting and more costs

Temporary Pattern for Fabricating Molds

Starting with an existing part...

Part must be rigidized or reinforced to maintain shape and dimensional accuracy
Demolding flanges added
Additional thickness added to account for shrinkage (sheet wax or similar process)
Runout must be added to the part to allow for trimming

Starting with 3D model... (Preferred Method)

Shrink is added to CAD model
Run out and flanges added to the model as needed
The modified 3D CAD model is used to CNC cut the temporary pattern

Process for Finishing the Temporary Pattern

The pattern is sealed to prevent absorbtion of moisture and help eliminate contamination
Top coated and surface detailed to finish requirements
Release agents are applied

Fabricating Molds for Manufacturing

Open-molding Fiberglass Mold Fabrication Process

Tooling gel coat applied over prepped pattern
Backup gel coat is applied
1 layer hand laid chop strand mat applied
2 additional layers of non-shrink chop applied allowing curing between layers
Reinforcements attached and encapsulated
Outer surface sealed with hot coat and labeled with identifying numbers
Demold from temporary pattern
Build first article part or FRP master if additional molds are required

Closed-molding Fiberglass Mold Fabrication Process

Tooling gel coat applied over prepped pattern
Backup gel coat applied
One layer chopped strand fiberglass mat applied
Two additional layers of non-shrink chop applied (allowing curing between layers)
Reinforcements attached and encapsulated
Outer surface sealed with hot coat and labeled with identifying number
Demold from temporary pattern
Apply pre engineered sheet wax to mold cavity to simulate finished part thinkness
Build in the sheet wax channels for vacuum seals and resin pathways
Mount infection ports and vacuum ports
Counter Mold Production
- RTM Lite - Gelcoat engineered wax simulation
- Hand layup one layer of chopstrand fiberglass mat
- Build up chop and reinforce as needed
- CCBM - coat engineered wax with silicone material

Fabricating Production Parts

Prototype Part for First Part Approval

Arrowhead will produce the prototype part according to our customer's design, specifications and requirements.

Prototype part is sent to customer for first part approval.

Build Required Fixturing and CNC Programming (As Required)

CNC Fiberglass Part Trimming

Construct Router Nest for Part
Setup Program for CNC Router

Hand Trimming

Hand Router Guide
Scribe Production Fixture
Gring Off Flanges

Running Production Parts

After all fixturing and first part approval are completed Arrowhead begins running full production of the parts on order.
Open Molded Parts
- Gel-coat is applied to the mold
- Fiberglass and resin is applied to the mold as required
- Core material is installed (if required)
- Additional layers of fiberglass and resin are applied as needed
- Part is pulled from the mold and trimmed according to prints or customer requirements
- Part is buffed and detailed as needed
- Fiberglass part goes through final inspection process and prepared for shipping
Closed Molded Parts
- Gel-coat is applied to the mold (if required)
- Fiberglass mat and core material is placed into mold
- Counter-mold is mounted into place
- Resin and catalyst are injected into the mold
- Part is pulled from the mold and trimmed according to prints or customer requirements
- Part is buffed and detailed as needed
- Fiberglass part goes through final inspection process and prepared for shipping

Arrowhead Plastic Engineering, Inc. provides this information as a very basic guidelines for the steps that you will need to get your fiberglass product design from the design phase to the final product. Each project may present specialized situation and product development that are not listed above.