Makino Provides Lift for A380 Wing Rib Production
AIRBUS Uses MAG4 To Drive Out Operational Costs
Production of the new AIRBUS A380 Super Jumbo Jet requires dramatic improvements to cost, quality and delivery for all aircraft components. The aircraft is intended to achieve a 25 percent reduction in cost per seat and a 15 percent improvement in fuel efficiency. These specifications have required AIRBUS to rethink their manufacturing processes both in terms of operation and machine tool selection.
According to Chris Harland, the A380 Wing Rib Project Manager at AIRBUS in, the United Kingdom, the nature of this business is changing. “The trend to monolithic parts is increasing. We must achieve economic run quantities of a single piece. It is now about process control due to high cost of individual pieces. Large batches and delays in inspection are a thing of the past due to the high potential cost of quality. It is no good to say we will inspect it later.”
These requirements dictated that the AIRBUS Filton plant make significant changes to their manufacturing processes. To meet these stringent requirements for the A380, AIRBUS Filton UK has created an advanced wing rib-manufacturing cell utilizing the Makino MAG-Series equipment.
The A380 wing rib manufacturing team set specific objectives when outlining the scope of the requirements for this new cell. They categorized these objectives under three headings: Quality, Cost and Delivery.
- Low scrap rate
- Low concessions
- High process capability
- In-process verification
- Machine utilization greater than 90 percent
- Multi-machine staffing
- Reduced inventory
- Reduced floor space
- Complete machined wing rib, start to finish, in 1 to 2 days
- Single piece production runs
With these specific objectives in mind, they began reviewing the initial designs of the new wing ribs. These wing ribs are massive, measuring as large as 3.1 x 2 meters. They are single-piece parts machined from an individual billet of a new, weight saving and high-tensile strength aluminum alloy.
Machine Investigation and Testing
The high-process capability requirements of the project led the team to realize they wanted a single-spindle machine over a multi-spindle gantry machine. This dramatically reduced the number of process variables they needed to control. This included only one set of tools, one fixture and a constant spindle interface.
To achieve their cost objectives, they determined that a single-spindle would need to be three times as efficient at removing metal as multi-spindles on gantry machines. In addition, they needed to achieve much greater spindle utilization.
AIRBUS was already utilizing high-speed horizontal machines for some of its wing rib production. They determined that the horizontal machining approach was the only way to proceed when they would be making this quantity of chips. “You can not afford for the parts to be lost under a sea of chips,” says Harland.
Given this analysis, AIRBUS established stringent specifications for an automated wing rib machining cell. They approached several vendors to determine which had equipment to meet their requirements, and narrowed their search to three potential vendors.
In order to evaluate these three vendors, AIRBUS designed a test part that incorporated all of the critical features from the family of wing rib parts to be produced. That test part design was supplied to each of the vendors to review. Based on their review, and feedback from AIRBUS, vendors developed a processing strategy for the part.
AIRBUS then went to each vendor to observe the test part actually being produced and inspect the part quality. In describing this procurement process Harland points out, “the published specifications mean nothing unless they follow through on the part production.”
The procurement team also considered the ability of the vendor to provide support and technical knowledge. Rapid machine installation and part process development were also vital project considerations. Additionally, AIRBUS reviewed which equipment and organization could ensure the most reliable equipment performance.
Making and Operating the Selection
After this detailed analysis and review, AIRBUS determined that the Makino MAG4 equipment with an automated pallet handling system was the proper selection for this project. The pallet handling system from Makino included an area for the storage of 6 pallets and a 90-degree pallet tilt station. This enables the parts to be loaded/unloaded on a horizontal surface and tilted vertically in order to position the parts to the horizontal spindles of the MAG-Series machines.
Makino installed their European demonstration MAG4 machine at the AIRBUS facility by March 2002. This enabled AIRBUS to immediately start the part process development activities on these new parts while the MAG4 machines for the system configuration were being produced. In September 2002, the installation of the two production MAG-Series machines and the automatic pallet handling system was complete.
Immediately after installation, the production machines were able to produce wing ribs for the A320. The rapid start up of production greatly improved the return-on- investment (ROI) for this system. AIRBUS was able to immediately start delivery of the wing ribs, with the entire first shipment needed by May 2003. Harland believes this goal should be achieved, which he feels is an impressive accomplishment due to the tight time schedule.
In reviewing the results achieved to date by this cell, AIRBUS feels they are well on their way to achieving their three objectives. They indicate the Makino machines have proven themselves to be reliable, with a very high (90+ percent) availability rate. This has been achieved while ramping up toward 90 percent utilization.
They also note that the spindle on the MAG4 is particularly robust. As with any new start-up, it has taken significant abuse, but without the damage that AIRBUS has experienced with other high-speed spindles and machines.
AIRBUS is achieving metal removal rates 2.6-times greater with the single-spindle than can be achieved on multi-spindle gantry machines. They also have some specific development activities underway that should enable them to surpass the 3-times capability they originally specified.
The ribs are being produced in a three-operation sequence on the MAG4. The first operation requires that the first side of the rib is rough machined, and then the rib is flipped over to the second side for rough machining. After it is relaxed, it is then finish machined on that second side during the second step. The rib is next flipped back over to the first side and finish machined in the third step.
The throughput time from start to finish for machining a wing rib is one to two days depending on the specific wing rib part being produced, which meets their original objective. The wing ribs are being run in single piece production quantities, dramatically reducing inventory levels. With the raw material cost of each rib exceeding 15,000 euros (approximately $16,000), this is a critical accomplishment.
Only minimal staffing increases were required for the wing rib production facility to support the additional A380 Super Jumbo Jet machining requirements. This is due to the multi-machine staffing capability of the Makino Machining Complex (MMC) automatic pallet handling system. Two operators are capable of loading and unloading the parts, with the Makino cell control software managing the machine scheduling, the indexing of the pallets to the machine, and the loading/unloading station.
Given all of these successes, Harland says the most important accomplishment has been the improved process control achieved from the single-spindle approach. “Internal process control is now a requirement of the aerospace industry. The highly efficient single-spindle horizontal machining approach utilized by the Makino MAG-Series machines enables AIRBUS to achieve this requirement.
“We are holding close tolerances of ±0.095 mm on the extremities of our parts. This is done with pocket thicknesses of 1.1 mm with a tolerance of –0.08 mm /+0.25 mm. We feel that the Makino machines can allow us to reduce to 0.8 mm with proven process capability.”
The production of these wing ribs is strategically important to AIRBUS. And, the Makino MAG-Series machines are providing the needed lift in manufacturing productivity to ensure AIRBUS is the worldwide leader in this capability.