Joshua Haston, Territory Account Manager at Connect 2 Cleanrooms explains how cleanrooms can support the achievement of greater degrees of accuracy to reliably repeat the production of micro parts.
For injection moulders, upgrading plastics manufacturing with a cleanroom to gain access to medical markets is a common move and a natural progression pathway. Cleanroom providers typically provide ISO 14644-1:2015 class 7 cleanrooms for such occasions. Having a class 5 cleanroom installed, however, brings additional benefits.
Micromoulding
Biplas Medical — a technical injection moulder in South Wales — had an ISO class 7 cleanroom installed when it introduced clean production in 2018. Earlier this year, the company took cleanroom production to another level when it needed an ISO class 5 cleanroom to house a micro-injection moulding machine to facilitate an Innovate UK grant project. Biplas Medical had joined a European consortium to develop a cancer diagnostics device, which, as it turned out, is produced using the smallest moulding ever made.
The larger parts produced by the micromoulding machine for a different project weigh approximately 3–4 g. By comparison, the parts required for the Innovate UK grant project weigh less than 0.1 g. These parts are so small that quality control (QC) inspection requires a microscope and camera.
The cleanroom ISO standard (14644-1:2015) dictates there can be no more than 10,200 particles of size 0.3 µm per m3 of air within an ISO class 5 cleanroom.1 To give an idea of scale, human hair has an average diameter of 100 µm and smoke particles are 1 µm. Achieving a microscopic level of environmental control is critical when producing micro parts as any contaminants would completely stop the products from working.
Since investing in the ISO class 5 cleanroom, Biplas has received micromoulding contracts for dentistry components and a two-shot biotechnology component that separates fluids and cells as they pass through the product. Both parts cannot be produced in conditions any higher than ISO class 5.
Benefits of clean production
A cleanroom creates a reliable and repeatable environment with controlled levels of airborne particulate. For manufacturers, this consistently clean production environment improves yield by reducing the number of parts that are rejected after QC inspection.
Since the introduction of its first cleanroom in 2018, Biplas Medical has reduced its scrap rate and increased its scope of supply by being able to offer packaging services. Clients also benefit from this value-added service, as components that are cleanroom packed and double-bagged are much easier to transfer into a cleanroom; they are also more reliable as is less chance of contamination causing defects.
Trained staff
Often, the biggest contamination risk in a cleanroom is people. Operatives need to be trained to develop skills and knowledge in this specialised area of the market. A cleanroom is a large investment; it is, however, only one component of a contamination control strategy. If behaviours aren’t learnt and adhered to then staff pose a contamination risk to the end product. Once trained, a workforce will be aware of the appropriate behaviours that will control the introduction, generation and retention of particles, in line with ISO 14644 standards.
Cleanroom design for plastics manufacturers
The challenge with creating a clean environment for medical plastics is that moulding machines produce contaminants during a cycle. A favoured solution is to part-enclose the machine in a clean environment so that the tool face is protected by clean air, but the hopper remains external to the environment. Purpose-built modular cleanrooms can be profiled around machinery, or designed with clean canopies that can be integrated directly with the machine. Canopies with retractable fan filer units can facilitate quicker tool changing procedures, thus reducing production downtime.
It is still possible to achieve a classified environment with full machine coverage. To achieve particle counts according to the levels dictated in ISO 146441, the cleanroom must introduce enough clean air to remove the contaminants produced by the process when operational.