Laser Projectors, Laser Assisted Layup technology - A407

 

Laser Projectors, Laser Assisted Layup technology
Document Type	Article
Document Identifier	407
Tags	Deposition
Prerequisites	Hand layup prepreg (Autoclave/Out-of-autoclave) processing

Introduction

To increase productivity, accuracy, and traceability of composite part manufacture, laser projection systems were developed to improve the speed, accuracy, and traceability of ply placement during layup. With a laser templating system, the system projects a light line to a high degree of accuracy on a complex 3-D surface, showing the operator where to position the ply or component. This is accomplished by having the laser light trace the outline repeatedly as fast as possible. Refresh rates faster than 30 Hz are perceived as a solid line by the human eye. The laser can also project the assembly part number, material fiber direction, and other instructions directly on the part where assembly is required. This significantly reduces operator workload, leading to fewer mistakes and faster turnaround times.

Significance

Laser systems are intended to decrease the amount of time and errors that occur during the hand lamination process in a production environment. Understanding how these systems work, how they are set up, and how they affect the operator is a key element in implementing them effectively. They also address the high skill level required in hand layup as laser systems replace some skill-dependent steps with accurate, repeatable ply positioning.

Scope

This article outlines the main features of these laser systems. This includes advantages, setup requirements, functions, and expected return on investment (ROI) from incorporating the equipment in the lamination process.

Setup of Laser Projection System

Safety concerns (Laser safety)

The word “laser” conjures images of high power systems. Many templating systems operate at low power and may meet eye-safe operating classifications, but supplier guidance and laser safety procedures must still be followed. Safety precautions from the system supplier, however, should be rigidly adhered to.

Positioning of laser projector over tool

The typical laser projection system operates at 3 m (10’) to 4.57 m (15') from the tool surface and covers an area between 3 m (10’) x 3 m (10’) to 4.57 m (15') x 4.57 m (15'). These coverage values apply when the projector is 4.57 m (15') from the surface. The projector should be positioned as close to normal to the tool surface as possible.

Single laser projection on tool

To project a template outline, the projector must be able to view the complete work area that is to be assembled. Due to the complexity and size of some composite tool shapes, multiple projectors may be required for ply layup on a single tool. Large convex and concave assemblies, typical of an aircraft fuselage or engine nacelle, may be difficult to see when only one projector is used.

Multiple laser projection system. For complex molds in which one laser is unable to cover the entire part

With the outline projected on the tool, the operator can quickly and accurately apply the material in the part build and proceed through the various steps required to complete an assembly. The time saving advantages of these systems are shown in the graphic below.

Expected operator time saved by the implementation of a laser projection system in the layup process

Expected operator time saved by the implementation of a laser projection system in the layup process.

Producing accurate projections in three dimensions

To project a 3D template pattern to a high degree of accuracy onto the tool surface, the system must first detect a series of retro-reflective target points located on the periphery of the tool surface. By comparing the position it detects these targets to a map of the targets in the computer model, the software can triangulate the position of the projectors relative to the tool surface. The computer then calculates and projects a laser beam onto the tool, outlining to a high degree of accuracy, the appropriate projection information (or the template). Typically, this would be the ply outline corrected for any known features, including existing material already laid up.

Retro-reflective target for laser projection templating system

A laser templating system typically requires at least four tooling target locations for projector registration. High-accuracy targets are placed in the precision-machined tooling locations. The targets have a silver retro-reflective center point. When the laser light hits the retroreflective target, the signal is reflected to the laser. This allows the laser to auto-collimate the target locations of the tooling. Once the four or more tooling targets are located, the laser projects the accurate outline of the ply on the 3D surface.

Once the operator has placed the ply, a simple controller (handheld, foot pedal or other) moves the projection to the next ply to allow the operator to position the subsequent plies. No realignment is required. This way, a considerable amount of human non-value-added work is eliminated. A laser projector is shown below.

Workstation components: adjustable height workstation, consumables rack, shadow board, and disposal bins

Additional Features

Which features are available depend greatly on the supplier. However, some common features include:

1. Multi-Tasking: A benefit where one system comprised of one or more projectors that can project on multiple parts in parallel. Each operator works independently from the same projection system. This allows the investment in a laser projection system to be shared multiple-fold over many part, offering multiple in productivity.
2. Text Projection on the part: This allows for additional instructions to be given to the operator, further decreasing the possibility for error. See example above.
3. Configuration management features: This can reduce paperwork and improve traceability. Steps are recorded for traceability in the computer and can show pictures and video. Wireless control for the operator and displays for operator information are all features to increase overall efficiency and error reduction.
4. Retro-reflective control: Laser detects a special retro-reflective material in a certain location, and executes a command. This can be used by an operator to cycle between steps in the layup when needed.

Time saved through Multi-tasking

Text instructions (left), Retro-reflective control (right)

ROI Inputs in Laser Projection

The cost savings below are to be compared against the capital cost of a laser projection system. The ROI can often be less than one year with a single shift usage, according to some manufacturers. The key advantages are the elimination of physical templates altogether. This alone proves to be very valuable, as this can increase cycle time by up to 50%, eliminate template storage completely, and reduce the frequency of operator error. Additional benefits noted are the automation of several traceability and management features, lower operator training requirements, and not updating physical templates with the new version of the part.

Direct benefits of implementation

1. No manufactured templates or drawings
2. Fast turnaround (< 1 day possible) vs 1+ months from start to manufactured templates available
3. Reduced personnel health problems
4. Full traceability of every step
5. Significant quality increase and reduced scrap parts
6. Increased accuracy (Typically +/- 0.030”)
7. Computer station can be reused for ERP/MRP/Work Instructions

Cons of laser projection system

1. Capital cost of purchase
2. Some computer infrastructure is required
3. Minimum computer competency required

Present Advances in the State of the Art in Laser Projection: AI integration

More sophisticated systems to further aid operators in the layup process are being developed. This includes the implementation of a new AI-powered vision, which can detect ply misalignment during deposition and the presence of foreign objects. It is expected that the implementation of these systems will allow for lower cycle times and reduced variability in the production of parts in the hand lamination process.

AI integrated laser projection system

Engineered materials (designed to have specific properties) made from two or more constituent materials with different physical or chemical properties. The constituents remain separate and distinct on a macroscopic level within the finished structure.