BEARINGS, SEALS & GASKETS FEATURE


Regulation (EC) 1935/2004 on materials and articles intended to come into contact with food (also known as the Framework or FCM Regulation); and Regulation (EC) 2023/2006 on good manufacturing practices for materials and articles intended to come into contact with food (also known as the GMP Regulation). Regulation (EC) 1935/2004 states: “A


name, reference number and batch or delivery number should identify each raw material, so that it can be traced, if necessary. The traceability of raw materials is achieved throughout the production chain and in-house by the delivery and/or batch reference numbers.” Food and beverage is the most obvious


means seal faces are protected from damage during installation. Who you purchase mechanical seals


from is also matter of choice. But for industries governed by food contact materials (FCM) legislation there really should be only one option: from a supplier who can trace the origin of each component of every seal with absolute certainty. These companies must adhere to


industry that must comply with the regulations. But crossover between food and beverage and pharmaceutical and bio pharmaceutical sectors is routine – the use of the dairy by-product β-lactose as an excipient is a typical example. So regulations governing food contact


materials (FCMs) must apply with equal weight in both sectors. The supply chains involved in the


production of component seals currently being imported into Europe from Asia


are complex. In pursuit of low costs the product has often been through so many links in the supply chain that by the time it arrives at the end user all traceability has been lost. It seems incredible that any mechanical


seal could contain, for example, antimony carbon, which looks like other harmless carbons but is, put simply, poisonous. Yet they have been seen on sites where the implications of it being misapplied could be disastrous. Companies which have FCMs who fail to


confirm the traceability of a mechanical seal are essentially building risk in to production processes at the same time as breaking the law. Is that a risk worth taking? Even for industries without FCM


obligations, specifying a fully traceable mechanical seal is surely common sense – as well as a clear indication of their commitment to quality, reliability and fair practice. Pound for pound, that’s got to be the surest measure of good value.


AESSEAL www.aesseal.com/en


Thin section bearings meet medical industry demands A


dvances in design as well as materials technology have resulted in the physical size


of many vital medical and laboratory devices being reduced. In one example, a manufacturer of proprietary disinfection and decontamination cells needed to design all-new medical devices as part of a larger installation. For this, however, the thinnest possible bearing was needed that could also allow the critical machinery it was installed in to deliver the highest positional accuracy over an extended lifetime. The design brief centred around applying these joint demands of reduced space and high precision into two key parts of the new cell. The first application was a medical


decontamination device for the containment of potentially contaminated matter in the form of human tissue or blood samples from patients. Here, the bearing needed to facilitate precision rotation in a design that permitted ease of operator use to reduce the possibility of human error. The second application in the cell was on an associated blood analyser, which called for a super thin bearing that could provide the required accuracy and precision to the testing element of the analyser in order for the unit to provide accurate test results, whilst at the same time streamlining workflow and easing maintenance. Not only did both devices need to offer


ultra-high positioning precision combined with the ability to deliver consistent repeatability over a lengthy service life, but they also required the smallest possible physical size for the machines,


together with a stipulation that the blood analysing device was required to spin inside a maximum radius of just 14”. Engineers at the Silverthin Bearing company,


which is represented in Europe by Oxford-based Carter Bearings, conducted trials using a shortlist drawn from its range of potentially suitable high precision thin section bearings before recommending the perfect match for the application. All Silverthin bearings are


manufactured to ABEC Standard using premium quality materials that are sourced only in the United States, helping to ensure high accuracy and long service life. The bearings are available in a variety of standard configurations, and can be specified as either sealed or unsealed units. For the medical device applications, sealed units were specified. Precision thin section bearings are available in four types from the company to suit most applications. In environments with axial loads present in


one direction, the A-Type angular contact ball bearing is recommended, and this also works well in radial or combined radial-thrust applications. However, Silverthin points out that the A-Type bearing should never be used alone to support moment loads or reversing axial loading. For these applications, Type C Radial Contact bearings are recommended: these are designed with deep ball grooves specifically to withstand


/ DESIGNSOLUTIONS


high loads. Although these bearings are used primarily in applications with radial loads, they can also withstand moderate axial loads, reversing axial loads, and moment loads too. However, for applications where significant moment loads will prevail, Silverthin recommends that designers consider its Type ‘X’ 4-Point Contact precision products. The X-Type, or 4-point contact


ball bearing, is ideal for moment loading applications and is designed with ‘Gothic arch’ raceways to create four contact points between the balls and the raceways. This design is said to be excellent for moment loading and also reversing axial loading. Carter says that the X-Type bearing can be used for other light loading conditions, but is not recommended in place of


the C- or A-Type bearing for pure radial loads. As a general rule, Silverthin advises that


when specifying this type of bearing for use with axial or moment loads combined with radial loads, the application speed (rpm) should be carefully considered. The company can provide application advice on


all aspects of thin section bearings, especially where space is at a premium and repeatability with absolute accuracy is vital.


Carter Manufacturing T: 01865 821720 DESIGN SOLUTIONS | DECEMBER/JANUARY 2021 33


Left: EU compliant mechanical seal


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52