Full Scale: Phillips-Medsize talks assembly processes
Today’s medical device and pharma industry assembly concepts can be complex. Bill Welch, chief technology officer, Phillips-Medisize, outlines how the company’s assembly concept is tailored to customers’ needs and the philosophy behind its scalability process.
It is estimated that 80% of a product’s cost and quality is determined during
the first 20% of the product development timeline. Whether the commercialisation
strategy involves in-house manufacturing or the use of a contract manufacturing organisation (CMO), early integration of a strong design for manufacture (DFM) and design for assembly (DFA) philosophy is critical to the device quality, cost and risk during clinical builds and commercial launch.
A strong DFM/DFA philosophy ingrained within the product development
process ensures manufacturing quality, cost, and risk objectives are met without losing
sight of HFE and the end-user device needs. DFx refers to ”design for x”, in which “x” may be any desirable attribute. At the component
level, DFM, or the more specific design for mouldability for injection moulded components,
refers to ensuring the product design conforms to the guidelines for the
manufacturing process to be used. This is especially critical in drug delivery devices,
since plastics are the most common material for mechanical components. Component-level DFM forms the backbone of the assembly process – regardless of the planned level of automation – since the process capability at the component level is necessary to reduce variation in the assembly process.
Similarly, DFA is done concurrently with product design – with quality, cost and risk of
the assembly in mind. At the component level, this includes addition of features to make
part handling, positioning, orientation and inclusion into the assembly or sub-assembly.
Component-level DFA ensures a mistake-proofing plan is established, which is also necessary to reduce variation in the assembly process. Additional benefits are gained by concurrent DFM/DFA throughout the product development process – for example to reduce
part count and eliminate high-risk assembly operations. Multimaterial or multishot,
moulding is one approach to combing components that eliminate complex assembly
operations and provide an elegant solution to design problems such as sealing to prevent
moisture intrusion. Early DFM/DFA team collaboration can then evaluate the return
on investment of the upfront mould tooling costs to reduce assembly equipment and
labour costs, prior to finalising the design.
While DFM/DFA must start at the component level to facilitate future scalability, the application of design for automated assembly (DFAA) is also applied concurrently
by the DFM/DFA team. DFAA is the next level, designing assembly processes
in which components are oriented, handled, assembled, and transported through
an assembly process without manual intervention.
• DFAA focuses solely on the automated assembly process, i.e, does not require human interaction
• DFAA application makes interim manual assembly processes to support builds prior
to automation build and validation easier. A device that is easy to assemble manually
will lend itself to automated assembly. Component-level DFA alone does not
develop processes suitable for automated assembly
• DFAA requires specialised automation engineering involvement in the beginning
phases of the development process to ensure automated assembly is taken into
consideration in parallel with other DFx. We do not attach these as we do not have space left for more text. DFM/DFA needs
to be an underlying philosophy truly integrated into the product development process.
Scalability to meet end-volume requirements
Increasing volume and varying production on a single system platform? This is feasible!
Scalability can develop the manufacturing scale from the initial low-volume
methods to the desired end-state volumes. In the case of a specialised, niche
drug delivery device this may mean progressing from low-volume, 3D-printed components
assembled by skilled technicians to a “manumation” assembly process conducted
by a trained operator. For commonly used drug delivery devices this typically
means developing processes to support engineering builds, then clinical supply,
and finally a fully automated or high speed automation process, supported
by developmental, single-cavity tooling and incrementally higher multi-cavity tools.
Flexibility, while related to scalability, has its own definition as it relates to two
primary concepts:
1. The ability to re-use assembly equipment modules when progressing from one scale
level to the next, to prove-out initial assembly concepts at lower scale and save time and cost by leveraging that same equipment
2. The ability to use all or most of an entire base flexible assembly line to produce multiple,
similar devices. In the case of pens and auto-injectors this typically means matching up a device product platform with an assembly platform, with changes being primarily in the components presented to the line following a controlled line clearance and changeover process.
DFM/DFA scalability considerations must be looked at with product development as part of a device manufacturing concept. This is a device-specific plan to scale component and assembly production capabilities to a desired end-state, typically with iterations for both components and assembly to meet engineering, clinical and commercial volume demand.
Creating a roadmap
A well-constructed device manufacturing concept will not only consider the volume,
costs and timing of device needs but also the regulatory requirements, risks and geographic considerations with each iteration of the scale-up plan. It provides structured, modularly designed assembly lines which can be extended at any time allowing fast retooling times. Essentially, the device manufacturing concept provides the “roadmap” to progress from initial, limited control engineering builds to the validated end-stage scale, meeting all quality system and regulatory requirements.
Core to the device manufacturing concept is a strong assembly systems foundation,
starting with the earliest manual builds to ensure the manual process is feasible for
scaling:
• Early manual builds need to establish the assembly sequence, fixturing, component
orientation, and assembly operations that will be carried forward to subsequent scaling
iterations
• Proper manual assembly is an enabler for higher level automation. Conversely, as
mentioned above, a DFAA analysis may lead to a more robust manual assembly
• Collect and analyse reject / scrap data to reduce variation with each subsequent
scaling iteration. It is imperative to ensure proof of concept has been achieved for
each process before making further scaling investment
• The user requirements specification (URS) for a manual process needs to set the
stage for the URS on the desired end-stage automation level. In some cases, it is helpful
to draft the URS for the high volume automation first and ensure as much as
possible can be learned from the manual process. In terms of flexibility, the re-use of
assembly platform equipment is typically limited. For example, a core single-track
assembly process cannot cost-effectively become a four-track system such as that
used for a typical high volume pen but a single-track line platform may be scaled
from manumation to semi-automation to full automation with upgrades to component
feeding, orientation, assembly and inspection / test operations which maintain the single-track configuration.
Equipment and tooling supplier selection is an important factor of the device manufacturing concept and consistent with DFM/DFA the suppliers should have early involvement. While the same suppliers can be used for all iterations of the same equipment and tooling, this is often not feasible or practical due to the technical focus, timing requirements or
global support capabilities of the supplier. For example, a quick-turn tooling shop
and local equipment builder may be necessary to maintain timelines for single-cavity
moulds and manual assembly fixtures but they do not have high-volume capabilities
or a global service network. In such cases it is imperative that the manufacturing unit
or CMO possess the project management, tooling engineering, and automation engineering
skills to develop suitable URS and ensure any lessons from initial stages are carried
over to subsequent scaling iterations.
Summary
Scalability for drug delivery devices begins with concurrent engineering via
DFM/DFA and the development of a device manufacturing concept. Use of common
definitions for classifications of tooling and assembly equipment can be used to align
the team on the concept and enable the tooling and automation engineers to specify, via the URS, the process requirements and select the appropriate suppliers for each scaling iteration. This means the manufacturing unit or CMO must have the capabilities to provide effective DFM/DFA and development of a device manufacturing concept, as well as the capabilities for the project management and technical execution of the plan.
Five levels or classifications of assembly
In order to facilitate development of a manufacturing strategy, it is useful to leverage a high-level common language and terminology for tooling and assembly classifications. These ensure all team members can understand and agree in concept as to the initial, interim, and final approaches to be taken to meet engineering, clinical and commercial volume requirements.
The table below shows the five classes Phillips-Medisize uses to describe different levels and types of assembly, and examples of Class II and III assembly lines.