Instead of being mechanically fixtured for inspection components on the other LK CMM at Alltrista are seen here being secured by suction
For over 10 years Alltrista Plastics has been using the same two CNC coordinate measuring machines (CMMs). Both systems have now been deemed inefficient. After many years of use, the software is beginning to crash, presenting the risk of physical collision or damage to the probe. Additionally, the accuracy and repeatability levels of the touch-trigger probing have been compromised.
Over time, plastic medical parts and assemblies that are being produced have become more complex. The user has to choose from half a dozen pre-set probe configurations, manually mount and calibrate it, and then sort through different programs on a computer and load the correct one. But LK Metrology’s Altera S 10.7.6 CMMs aim to streamline and automate the whole process.
About Alltrista Plastics
Established in 1993, but with roots dating back to the 1800s, Alltrista has five manufacturing locations. The company is also credited as the first facility within the Jadex group to be powered by renewable electricity. The American company specialises in plastic injection moulding of devices like drug delivery systems, and packaging including contact lens blisters, for the medical, pharmaceutical, and nutraceutical industries.
LK Metrology upgrades Alltrista Plastics' quality room
In addition to the two Altera S 10.7.6 CMMs, Alltrista Plastics has also adopted the CAMIO 3-axis scanning and reporting software and Renishaw’s SP25M probe and PH10M motorised indexing head. The latter two effectively create two sensors in one, enabling continuous path tactile scanning and touch-trigger probing of discrete points. LK Metrology did explore the possibility of retrofitting the older CMMs, but the cost was too high. Additionally, the machines were becoming too inefficient for the tasks required of them.
Peter Makosa setting up one of the reduced-height LK Altera S CMMs in the temperture controlled inspection room at Alltrista's Christchurch factory in the UK
This new set-up has allowed for a vast improvement in the company’s metrology productivity, especially with the addition of the Renishaw matrix plate which provides the accurate placement of parts for inspection. The setup facilitates the fixturing of samples, speeding up measuring cycles, and it drastically reduces the need for human intervention while reducing the risk of errors occurring.
“I operated LK CMMs for several years when working for an aerospace manufacturer, which had standardised on their use,” said Peter Makosa, Quality Manager at Alltrista Plastics. “When Alltrista decided to upgrade its quality room, we approach four potential machine providers including the incumbent supplier. LK’s response was by far the most comprehensive.”
He continued, “It carried out an online demo on one of our parts and another trial when we visited Castle Donington. It was the only company to initiate a comprehensive on-site survey at our factory to check the feasibility of machine installation.”
Alltrista Plastics house its injection moulding machines in one Class 7 and two Class 8 clean rooms at Christchurch. In the last decade, medical devices have seen an increase in the proportion of turnover, and variety and production volume, with throughput rising from 30% to 50%. A number that is still rising. Additionally, the industry is trending towards tighter drawing tolerances on newly designed products and more stringent geometric dimensioning and tolerancing (GD&T) requirements.
The plastic injection moulding company undertakes a rigorous validation process at its base in Christchurch. At the outset of a new production run, for example, 30 shots containing 15 components each will be checked whether they meet the customer's process capability. Components are also checked for any inaccuracies in the measurements.
Key specs of the Altera S 10.7.6 CMM
- Acceleration from 2,306 mm/s2.
- Multipurpose compact CMM.
- Repeatability from 1.7 μm.
- Typical applications are likely to be found in aerospace, automotive, medical, and other industries.
- Velocity from 762 mm/s.
- Volumetric accuracy from 1.8 μm + L/400.
How have the new CMMs impacted Alltrista Plastics' business?
Following the installation of the new CMMs, LK Metrology wrote core programmes for four of Alltrista Plastics’ main customers relating to the inspection of components. The metrology solutions and services provider also devised a PC screen dashboard, making the whole process menu driven. Each company only needs to select its icon to reveal every part that is injection moulded, specialised to their own processes.
However, before the process can begin, a selection of components needs to be positioned on the granite table. To speed up this procedure, LK Metrology included a Renishaw matrix plate. The plates were secured from underneath using anchor bolt holes, avoiding the use of retaining clamps projecting from the table surface. A standard operating procedure (SOP) is included in the on-screen dashboard, which shows the user the exact location across the numbered grid of holes on the matrix plate where the batch of fixture samples should be.
The whole process drastically reduces the amount of human interaction, with the system positioning components accurately. Program instigation is completed using LK Metrology’s CAMIO system, and CNC inspection and automatic reporting hope to eliminate all potential errors. Makosa described the system as “foolproof.”
“On the basis of the measurements taken, bearing in mind that LK machines are taller than our previous CMMs, the manufacturer offered to reduce the height of the Altera S models during their build so they would fit comfortably through our doorways and in our refurbished inspection room,” said Makosa.
Additionally, Alltrista Plastics required more data to increase its understanding of specific features of mouldings. For example, the flatness of sealing faces, freeform profiles, and chamfers. Fulfilling this need, Renishaw’s scanning probe provides additional feedback and information to the production department, allowing for fine-tuning. The increase in data also benefits Alltrista’s customers, as they receive more detailed reports, allowing them to understand what the manufacturer has done for them. Reports are now displayed on locked PDFs generated in CAMIO, instead of Excel spreadsheets, improving the layout.
Looking forward to the future, Alltrista Plastics was supplied with the Altera S controllers and CAMIO software which accepts data input from laser scanning sensors. LK Metrology included these products in case the plastic injection moulding company wishes to increase the complexity of its plastic devices in the future.
Makosa concluded his thoughts on the collaboration by saying, “What finally clinched our decision to opt for this supplier were the favourable price of the equipment, the knowledgeable engineers that dealt with us throughout the entire sales process and the company’s reputation for good after-sales service.”