Airtech
Published

Shop practice impacts drilling success

When you're drilling holes in composites, there are many variables that must be considered. Some factors that have an impact on success are process and shop driven. The following are industry best practices that have been demonstrated to maximize hole quality and drilling efficiency with composites.

Share

Matching the machine tool to the job can’t guarantee success (see HPC's feature article on that subject, "Hole ambitions? Optimize! Customize!" under "Editors Pick's" at upper right). Some factors are process and shop driven. The following are industry best practices that have been demonstrated to maximize hole quality and drilling efficiency with composites.

Invest in strong, stable fixturing. “The sturdier, the better,” says Peter Diamantis (AMAMCO, Duncan, S.C.). “Unfortunately, this is not always easy to do. You are always going to have vibration during a machining operation. So you have to compensate for that.” Alex Harding, COO at Cajero Ltd. (Isle of Sheppey, Kent, U.K.), notes that a properly designed fixture will support the part “beneath the drill zone to avoid spring-back on drill exit.”

Use drill motors that can sense a change in material density.Motor technology is available that can react — and change speed — when the drill tip passes through one material into another. In a composite/titanium stack, the drill slows and introduces micropecking of the metal. “CNC programming can do this automatically,” says Diamantis. “A sensor can be installed with positive drive feed motors to achieve the same result.”

Follow the prescribed drilling regime. In manual operations, “if a machinist gets tired pushing a drill, he is going to pursue a different way of drilling or using a different drill bit,” says Diamantis. “The operator will always prefer what is most comfortable. That always has to be kept in mind when trying to optimize hand operations. No matter how efficient a process is designed to be, it won’t save any money or time if the workers won’t follow it."

Techs at SECO Tools (Fagersta, Sweden and Troy, Mich.), which was acquired by Sandvik Coromant (Amsterdam, The Netherlands) earlier this year, describe a case where an optimized tool was developed for an asymmetrical composite and metallic stack. The customer, however, soon returned, complaining of premature tool wear and poor hole quality. SECO discovered that 90 percent of the holes were drilled from the top, but 10 percent were drilled from the bottom due to access issues. For those holes, of course, the materials stack sequence was reversed — the optimized tool was optimized no longer and suffered damage as a result.

Don’t stint on dust and debris removal.Recirculating debris and dust reduces tool life, creates undesirable heat and can damage part integrity, says Harding (Cajero Ltd., Isle of Sheppey, Kent, U.K.). Removing debris during drilling also saves time downstream. For example, honeycomb cells no longer need dust suctioned out or edges cleaned, potentially savings thousands of hours over the life of a program. And when one-up assemblies are drilled, the resulting increase in productivity can be lost if poor control of dust and debris forces disassembly for cleanup. Those saved hours conserve money that will easily pay for a state-of-the-art vacuum system.

“We can help here as well,” offers Harding. “We work with the manufacturer to develop machining of the whole assembly that eliminates cleanup required downstream, as well as scrap or rework, so that no disassembly is required.”

Airtech
Smart Tooling
HyperX Software for Composite Structural Analysis
Airtech
Large Scale Additive Manufacturing
Release agents and process chemical specialties
CIJECT machines and monitoring systems
HEATCON Composite Systems
IRIS Ai-enabled Camera
CompositesWorld
NewStar Adhesives - Nautical Adhesives
Visual of lab with a yellow line

Related Content

Core

ATL Composites collaboration advances kite-foil board production for Paris Olympics

Breiana Whitehead, pioneering Australian kite-foil sailor, spearheads board design intricacies with ATL Composites to enhance her performance ahead of the July 2024 competition.

Read More

VIDEO: Recycling and machining carbon fiber scraps

Elevated Materials has partnered with ‪Toray Composite Materials America, Inc. to collect and upcycle reclaimed carbon fiber scraps into large billet laminates, which can then be cut into various parts using CNC mills.

Read More
Aerospace

From the CW Archives: Drilling is not for the faint of heart

This edition of From the CW Archives revisits CW’s first plant tour — a visit to the F-35 FAL in Fort Worth, Texas — and a story by Ginger Gardiner a few years later. Both offer lessons on how to perform stacked drilling through composite and metallic materials. 

Read More
Carbon Fibers

Filament winding increases access to high-performance composite prostheses

Steptics industrializes production of CFRP prostheses, enabling hundreds of parts/day and 50% lower cost.

Read More

Read Next

Machining/Drilling

Optimizing, customizing composites hole drilling

Matching the drill tool to the job can save thousands of man-hours and millions of dollars.

Read More
Aerospace

Orbital Drilling enables “one-up assembly”

Orbital Drilling, a technology patented by Novator AB (Spånga, Sweden) offers multiple hole sizes from a single drill tool.

Read More
Airtech International Inc.