Albert Browne installs Schmidt assembly system

Published: 15-Aug-2011

Ensures precise pressure for inserting stoppers into vials for protein testing kits

Albert Browne, a UK supplier of infection prevention products, is using a custom-built assembly system, developed and manufactured by UK-based Schmidt Technology, to automate a critical stage in the production of protein detection kits for use in the medical and healthcare sectors.

The new system, based on Schmidt Technology’s latest 405 servo press, is providing high levels of accuracy and applied force in a delicate application, while helping Albert Browne to double productivity and ensure product traceability.

Founded in the 1930s, Albert Browne, based in Leicester, UK, is today part of the Steris Corporation and specialises in the development and manufacture of chemical monitoring and contamination detection kits for use in steam and chemical sterilisation and decontamination systems. They are typically used in hospitals for cleaning surgical instruments, gowns and endoscopes.

One of the company’s main product lines is the Ninhydrin Protein Detection Kit, used for detecting protein residues that may remain on surgical instruments after they have passed through a washer-disinfector.

A key part of the kit is the supply of small test vials containing ninhydrin reagent in a gel form, which reacts to show the presence of amino acids, peptides and protein residues, plus vials of dried arginine.

Each vial measures 10mm in diameter and 150mm in length and is pre-filled with gel before an airtight stopper is inserted and the vials packed with other test items and instructions prior to shipping. Until recently, the stoppers were inserted by hand, which was a time-consuming and relatively slow process. The process was also impossible to regulate consistently so that stoppers were always inserted with the optimum force to guarantee an airtight seal.

The semi-automatic system developed by Schmidt incorporates a stainless steel rotary bowl-feeder, a pick and place mechanism, six-station rotary table and a 405 servo press. Individual vials are hand loaded into each of the six location inserts on the rotary table. As the table indexes round, a stopper is first positioned by pneumatic grippers into the opening of each vial, before being presented to the press, which then forces the stopper home.

“It is critical that we strike a delicate balance between applying sufficient force to ensure that each stopper creates an airtight seal, preventing the volatile ninhydrin from evaporating, but not so much force that the relatively soft plastic stoppers spread in the neck of each vial and become impossible to remove by hand,” said Steve Brown, production manager at Albert Browne.

The Schmidt system uses dynamic closed loop force control to regulate the force applied to each stopper as it is pressed into the vial, to within plus or minus 0.5N.

The system is also capable of fast ram speeds – of up to 200mm/sec – to improve cycle times, but can be instantly controlled to reduce speeds to just mm/sec over the final few millimetres of travel as each stopper is pushed home. This can be achieved consistently, at a resolution of less than 2.4 micron and a level of repeatability of under 10.0 micron.

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