The concepts of return on investment (ROI) and payback time are second nature to practicing engineers but that doesn’t mean that the associated calculations are always straight forward. When it comes to assessing analytical equipment then the upfront costs can be relatively easy to determine, but the potential return is significantly more difficult. Powder testing equipment is a particularly interesting example for the consideration of this issue. Testers for the measurement of powder flowability vary in price – from just a few thousand to tens of thousands of dollars – but also in terms of sophistication, level of automation, data quality and relevance.

In this article we consider how powder testing delivers value focusing on the features of off-line and at-line testers that are associated with higher returns. The aim is to support sound decision-making around the selection of a tester, based on rigorous economic assessment.

<strong>The economic benefits of powder testing</strong>
Maximizing the ROI on a powder tester relies in the first instance on realistically establishing what benefits an appropriately specified powder tester might deliver, and the value associated with them. Powder testers are used to assess powder flowability from early R&amp;D through to QC with each stage of the manufacturing cycle offering potential for economic gain.
• Product development and formulation: In R&amp;D, powder testing can accelerate a program to a more successful conclusion. The most substantial economic prize is reduced time to market, which can dwarf other returns, but there is also potential for savings on pilot scale studies which can be both time-consuming and expensive, and for broader gains in experimental productivity.
• Equipment design and selection: Powder testing that identifies optimal processing equipment for a given powder maximizes the likelihood of trouble-free operation over the long term, delivering economic returns by enhancing manufacturing efficiency - fewer unplanned shutdowns, for example, faster commissioning and/or less product re-work. For companies that specialize in the design and provision of powder processing solutions the ability to efficiently specify optimal solutions directly boosts productivity.
• Process operation and troubleshooting: When powder processes fail to perform consistently powder testing can elucidate the cause of an operational problem and provide a secure foundation for the development of a rational solution. Solving operational problems, particularly long-standing ones, can deliver a significant economic dividend, by reducing production costs or increasing throughput, often with minimal capital expenditure.
• Quality control (QC): In QC, powder testing detects a sub-standard raw material or product before it enters the plant or is released, respectively. The reliable detection of poor-quality raw materials avoids operational issues ranging from out-of-specification production to an unplanned shutdown, while the robust detection of compromised product quality safeguards profit margins and company reputation.
The valuable differences between powder testers
Commercially available powder testers (Figure 1 - 3) vary considerably in terms of their ability to deliver these outlined economic benefits primarily due to substantial differences in:
<img class="alignnone size-medium wp-image-4346" src="https://microbiozindia.com/wp-content/uploads/2020/03/Figure-1-247x300.png" alt="" width="247" height="300" />

Figure 1: Simple manual testers, such as those that measure flow through an orifice, are low cost but often lack the repeatability, sensitivity and relevance to directly address powder processing issues.
<img class="alignnone size-medium wp-image-4347" src="https://microbiozindia.com/wp-content/uploads/2020/03/Figure-2-151x300.png" alt="" width="151" height="300" />

Figure 2: An automated uniaxial tester measures a single variable with high repeatability and reproducibility and can be a cost-efficient choice for routine testing in, for example, QC.
<img class="alignnone size-medium wp-image-4348" src="https://microbiozindia.com/wp-content/uploads/2020/03/Figure-3-223x300.png" alt="" width="223" height="300" />

Figure 3: A powder tester that offers multiple test methodologies, in this case dynamic, shear and bulk property measurement, provides multi-faceted powder characterization that can be particularly valuable when faced with more complex processing or performance issues.
<strong>• Relevance</strong>
Though many powder testers measure just a single number, some generate multiple parameters, thereby providing more comprehensive insight into powder behavior. Techniques and testers also differ with respect to the extent to which the conditions applied during testing can be varied, with some allowing control of the test environment to simulate process conditions, to a greater or less extent.
The net result of these differences is that the data generated by a tester may, or may not, be relevant to the process of interest - the tester may detect a difference between samples that shows no correlation with powder performance in the process or application of interest. This issue, which is unique to powders, can significantly erode the value of a tester, particularly for more demanding applications.
<strong>• Repeatability, reproducibility and sensitivity</strong>
These three parameters define the ability of a tester to detect difference, to differentiate one sample from another. A frequently encountered problem in powder processing is that materials classified as being the same go on to perform differently, because the tester is unable to provide adequate differentiation.
Repeatability is a measure of instrument precision, the variability associated with repeat measurements of the same sample by the same operator, while reproducibility additionally incorporates operator-to-operator variability and errors associated with sampling and sample preparation. Sensitivity is an inherent characteristic of a technique but can also be affected by both repeatability and reproducibility so two instruments that use the same technique may differ in terms of sensitivity because of their design. A tester that uses an inherently sensitive technique and is engineered to deliver high repeatability and high reproducibility will be the most powerful and discriminating tool for testing closely similar powders.
<strong>• Automation</strong>
The simplest powder testers are manually operated, with minimal automation. Upfront equipment costs are correspondingly low, a downside being that the labor cost for each measurement can be relatively high. Automation tends to be associated with more sophisticated techniques but keeps cost per measurement to a minimum and productivity high. Initial equipment costs for an automated instrument will reflect its greater complexity but a consideration of lifetime costs, factoring in labor based on typical usage, may more fairly reflect the economic merits of automation, over the long term.

Equally importantly, automation offers the advantage of ensuring that a rigorously specified method is consistently applied, boosting the repeatability and reproducibility of a technique. It can therefore be a crucial foundation for achieving the sensitivity and discriminating power required for tougher powder testing challenges.

The following examples provide a simple illustration of how the relative importance of these features varies from application to application and demonstrate in principle how to estimate a ROI to justify investing in a suitably specified tester.
<strong>Powder tester investment example 1:</strong>
An equipment supplier specifies turnkey powder processing solutions based on analyses of customer powder samples. The requirement is for a powder tester that will support the efficient identification of optimal processing equipment for a given powder and minimize the need for pilot scale trials.
This application calls for a tester with broad relevance, one that is suitable for powders across the cohesivity spectrum and that generates data that can be robustly correlated with a range of different unit operations. An instrument that measures multiple powder properties is likely to be particularly advantageous here, to enable the detailed characterization of each new material, and the development of a robust specification for powders that perform well in individual items of processing equipment.
In terms of economic return, accurate and relevant powder testing has the potential to accelerate the workflow of the whole company, boosting productivity at the specification stage, reducing the need for at-site modifications, and supporting trouble-free commissioning. If the average time taken to develop and deliver each solution is reduced from t1 to t2 then it is possible to serve an increased number of customers in each year, delivering an associated annualized economic gain that can be calculated from average profit per customer.
Annualized gain = Average profit per customer * Annual number of customers per year * ((t1) / (t2))
For example, if the time taken to develop a solution is reduced by just under 7% from 150 hours on average (t1) to 140 hours (t2) and the company currently delivers 45 solutions per year, each with an average profit of $20,000 then the annualized return on the powder tester is more than $60,000, assuming a market for increased sales.
<strong>Powder tester investment example 2:</strong>
A powder supplier can potentially access a market that pays a premium price, higher than that obtained for the current product, but only if product quality is consistently high.
This application calls for a tester with high repeatability and reproducibility but may be met by a relatively simple technique, depending on the end-use of the powder. Testing will be routine and relatively frequent, to safeguard product quality, so automation is likely to be advantageous.
Calculating the return in this example is straightforward since success will mean a premium price for every ton of product.
<strong>Annualized gain = Average annual throughput * Additional profit per ton</strong>
For a plant with a throughput of 10,000 tons per annum, making an additional $60 per ton of profit equates to a gain of $600,000 per year, a significant gain which highlights the potential benefit of being able to access higher value markets.
<strong>Looking ahead</strong>
A powder tester selected based on a realistic evaluation of likely financial return, with the performance required for success, can offer an extremely attractive ROI. Accessing such return typically relies on choosing a tester that reliably differentiates powders that perform differently, provides data that are relevant to the process of interest, and offers an appropriate level of automation. Opting for a powder tester that robustly fulfils rather than unnecessarily exceeds requirements is critical for an optimal return.
The focus of this article is off-line and at-line testers, but in-line powder flow measurement is becoming increasingly well-established as new commercial solutions are introduced. By providing real-time process monitoring these systems offer complementary opportunities to enhance manufacturing efficiency and the potential to further boost the profitability of powder processes.