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Fixing a sticky situation

16th June 2017

Posted By Paul Boughton


Natoli Engineering’s NP-400 tablet press
Table 1. Compressibility index using Hausner Ratio
Multi-tip tooling used during development
Tablets ejecting during NP-400 FAT
Die table and tooling during NP-400 FAT

Randy Jung reveals how investing in a new tablet press helped solve production issues for a cosmetics company 

One of the USA’s leading tableting experts recently completed a successful factory acceptance test (FAT) with an international top-tier cosmetics company.

The customer specialises in producing, marketing and selling handmade cosmetics through more than 700 retail stores in over 44 countries worldwide. It also has a line of tableted products in the oral care segment.

Ramping up production of these oral care products worldwide, the company was using two existing tablet presses but expansion and creation of a new line of products left it with manufacturing issues. 

Initial evaluation

Initially, tooling options were tried to alleviate tableting issues. It became clear that simple tooling changes would be insufficient in meeting the increasing needs of the customer.

Natoli’s technical experts evaluated the customer’s best-case scenario and configured a solution for its unique formulation to increase production, improve tablet quality and reduce cost. Familiarity in working with the customer was key to Natoli’s success in creating a solution that met the customer’s needs.

Evaluating customer needs – compressibility issues

To begin the process, product formulation samples were received for testing. As part of the customer’s brand and commitment to using all- natural ingredients, it educated the Natoli team about how formulations were prepared entirely by hand.

The team then learned about the amount of R&D completed by the customer, and committed resources to helping improve its oral care product line. During the assessment, the compressibility of nine different products was completed using the Hausner Ratio (see Table 1). These assessments found that all nine of the products fell in the poor to extremely poor ranges.

Press optimisation 

Knowing that customisation would provide the best final product and fewer manufacturing issues, the NP-400 tablet press was selected as the press of choice to optimise manufacture of the customer’s tablets.

To optimise the NP-400, a compression study was completed using Natoli’s RD-10A single station R&D press. During the compression analysis, a baseline was calculated for production scale- up. Noticing a considerable number of customer-supplied sample tablets showed signs of capping, sticking and weight inconsistencies, attempts were made to recreate the issues.

For full understanding, it was necessary to find the effects of different main and pre-compression forces on tablet quality and hardness.

The analysis showed that compression forces over 19kN, recreated the capping and sticking issues. Knowing the customer’s growth plans, a multi-tip tooling design was recommended to increase production and reduce cost. 

Troubles implementing multi-tip tooling

The initial NP-400 pressrun used three-tip multi-tip tooling and was successful, but was not the win hoped for.

The product would only run in the range  of 15 to 20 revolutions per minute producing 59,400 tablets per hour. At these low speeds, the formulation bridged in the hopper transition – product was not consistently flowing through the acrylic feeder tube. There were also concerns about the consistency of the tablets due to filling issues of the dies.

First, an optional vibratory hopper probe was installed to overcome the formulation bridging issue. Then, the feeder was optimised by using a higher-speed motor, redesigning the feeder paddles and lowering the paddles closer to the dies. These changes increased production speeds and improved the tablet consistency issues.

After implementing the new vibration unit and feeder design changes, the customer’s products ran at a rate of over 178,000 tablets an hour during the two-day FAT. In total, nine different products in two tablet designs consumed 96.4kg of powder per hour during the test.

Impacting the customer’s bottom line

The impact for the customer is considerable. Not only was Natoli able to solve several manufacturing issues through innovative research, design and engineering, the production capabilities have also increased approximately threefold. These capabilities will allow the customer to run a single press and potentially house worldwide production in a single facility.

The customer can now produce 5,091 bottles of product per hour at a selling price of US$9.95. This means that the NP-400 tablet press increased the customer’s revenue potential by US$46,395 per hour over its existing presses.

Randy Jung is with Natoli





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