BLISTERS: Keeping Up with Feeders
Dedicated feeders can achieve high blister fill rates for distinctive solid-dose forms.
Cold Form 4000 laminate from Reynolds Flexible Packaging features an added layer of PVC film for blister dent resistance.
The goal of blister feeding is accurate and fast placement of the tablets or capsules into the blister cavities. As they are designed for specific tablet shapes and blister formats, dedicated feeders are increasingly favored for efficient blister filling.
Simpler feeder formats, however, have their place and can reduce tooling costs. In the final analysis, the choice of feeder format is influenced by the characteristics of the product and the blister design.
“Our customers are moving toward dedicated feeders,” says Kenneth Spiegel, blister packaging manager, The Elizabeth Companies (McKeesport, PA). “Simpler feeding devices are easier to set up but often result in lower production rates. In many cases, manual inspection must be performed after filling. Ultimately, you are reducing output and increasing labor costs.”
Pharma companies are developing more uniquely shaped tablets to impart a distinct identity for the product, and make the solid-dose forms harder to copy. Tube-style feeders that use dedicated tubes and drop chutes ensure high fill rates for these hard-to-handle products, says Frank Brown, blister feed systems product manager, Aylward Enterprises (New Bern, NC).
In Aylward’s XYZ Feed System, tablets are oriented in an upright position before being introduced into fill tubes. A twin-shuttle system always releases a single product through the drop chute. For tapered tablets prone to “shingling” or overlapping, Aylward provides its patented Spyro tube design that prevents tabs from locking up in the tubes.
The Elizabeth Companiesï¿½ Combo Feeder can be tested to meet customer specifications. Click here for a video.
“We have seen increased use of alu/alu blisters with the growing demand for blister barrier,” Brown says. “This is another specific application where a dedicated solution is beneficial. A brush box will brush the tablets out of the shallower alu cavities resulting in very expensive scrap materials. Our tube feeder is placing the tablets into the formed cavity.”
Tube-style feeders are favored for limiting product contamination. They also prevent dispersal of product dust that might interfere with sealing. “Contamination is an issue particularly in packaging of prescription drugs,” says Klaus Gehlert, president, Gemel Precision Tool Co. (Ivyland, PA). “Customers have concerns about contact with the part. Also, in brush box filling, when bulk amounts of products are brushed into open blister cavities, dust residue can settle on the webbing and interfere with the lid stock seal.”
“The cleaning and swab testing (required with brush or paddle boxes) between lots is expensive and time- consuming,” he adds. “Brush boxes are becoming increasingly obsolete.”
One advantage of tube-style systems is that they articulate off the web. This has driven use of these custom solutions by pharma companies, says Ben Brower, VP sales and marketing, Micron PharmaWorks Inc. (Odessa, FL).
CLEAR OF THE WEB
In the Combo Feeder from Elizabeth Companies, a mobile carriage is used to move chute or brush box formats across the web for filling on intermittent blister machines.
The feeder moves down for filling when the web is static after indexing on an intermittent blister machine, then lifts out of the way after filling. A brush box, by contrast, is in constant contact with the web. Its perimeter edges can snag the web, throwing it out of registration, or tear the web, Brower says.
In the Aylward feed system, the feeder is installed on the firm’s XYZ touch frame. Mounted via a base plate onto the blister machine, the frame cantilevers over the web to position the feeder cassette. There is no contact with the formed web during the feed cycle. The frame can be fabricated with stepper or servomotors for controlling movement in any of three axes, Brown says.
“The XYZ frame is a programmable system that we provide for continuous- and intermittent-motion formats,” says Brown. “If more dwell time is needed for accurately dropping the product, a “sweep motion” function can be programmed and stored as a recipe. Using the touch frame with the feed system we guarantee a minimum of 99.9% filling efficiency.”
Gemel supplies feeder solutions for blister thermoformers from manufacturers including Uhlmann, Bosch, Klöckner, and IMA. Gemel’s GFS II line supports toolless installation with product-fitted change parts from Aylward and SimTap. The feeder cassettes feature the firm’s patented O-ring gating system. The O-ring gating uses top and bottom gates for holding and releasing product for staging to the filling tubes. “We can gate 20 tubes at one time. O-ring gating provides a significant cost savings over a ‘T-Pin’ system, and is much easier to clean,” Gehlert says.
The F=1-rated 3CPak compliance format from Colonial Carton Co. can be fabricated on standard blister card machines.
Product dust is removed inside the shaker or feeder bowl with a vacuum system.
The GFS II line for intermittent blister machines is offered in a 300-mm index length, and a 600-mm length for applications where two different products are put into one card per index.
Tube-style feeders with dedicated tubes and dedicated drop chutes most often come to mind when “dedicated feeders” are mentioned. But any feeder system configured for a particular application is a dedicated solution. “The only true generic feeder is the flood feeder (brush box), which doesn’t care about the tablet you are running or the web running underneath,” says Brower.
In filling blister cards by random chance with the assist of gravity, brush boxes are sometimes less accurate, and require manual inspection after filling in some applications. Yet they can achieve high fill rates in others, such as with convex pills that fall easily into the cavities.
“Tube-style feeders are by far the most used in the industry today, but the brush box is alive and well,” Brower says. “In some applications, you need a brush box.”
When simpler formats are used, tooling costs are significantly reduced. The cost of format changeovers also has to be considered.
“Tooling changes can usually be performed fairly quickly,” Brower says. “But if you are changing between a dedicated format and a brush box, you are pulling everything off including the frame. This is a good time to have the system mounted on a mobile cart that can roll up and dock to the machine. If the flood feeder stays on the machine, the brushes and box panels can be washed out or replaced between runs with minimal operating cost.”
In the Aylward XYZ system, the touch frame stays on the machine when feeders are switched. “When you need to change the feeder out for another format, we simply retract our pin cylinders and remove the feeder cassette,” says Brown. Customized chute-style and vibrating-ramp formats can provide high feed rates, with lower tooling costs compared with tube-style feeders.
Elizabeth Companies offers feeders with chute widths and configurations specific to the width of the tablet and blister format. One of the company’s customers was filling 60–70 packs a minute, feeding pentagon-shaped tablets with a brush box format. During production runs, they stationed a person at the machine to manually fill pockets that were frequently missed, says Spiegel.
Elizabeth built a vibrating-ramp feeder, consisting of a chute angled at 45 degrees on top of a linear vibrating table that moves constantly. The system features top and bottom chute notches that precisely hold the tablets flat and oriented in fixed positions without touching the channel sidewalls.
“It took us four weeks to figure out a solution to run at the speeds they were hoping to achieve. We used a high-speed camera to observe the behavior of the tabs,” Spiegel says.
The solution consistently achieves 100 blisters a minute with a 99.99% fill rate, and eliminates the need for direct supervision, he says.
To help customers determine the best feeder solution, Elizabeth Companies offers free testing services. Alternative formats are run on a test bench, with tablets and preformed PVC supplied by the customer. Feed rates are tested for various styles of feeders as the bench runs the PVC in a loop mimicking a blister machine.
“When feed rates are deemed optimal for the application, we will send the customer a video showing a two- or three-minute run so they can see the potential for performance gains over their current feeder system,” Spiegel says.
The company demonstrated its patented Combo Feeder at Interphex, InterPack, and PackExpo this year. Twenty systems have been sold in Europe since the unit’s launch two years ago. The McKeesport facility uses one for testing purposes.
The combo feeder supports tool changes by using a common base for three feeder formats—brush box, static chute, and vibrating ramp. Formats are switched out in two minutes, without the need for pulling the mechanical drive system and controls. Centralized controls and mechanical drives improve productivity and operator safety by increasing uptime and reducing setup and handling. Economical change parts and shared housings reduce ongoing expenses when changeovers are required.
“If you are using a tube-style feeder and move to a brush box, you would have to dedicate two hours for removing the feeder base plate,” says Spiegel.
For high-speed filling on intermittent-motion machines, the Combo feeder can be used with a mobile carriage. The carriage is a linear slide that synchronizes the movement of the feeder with the movement of the web, moving left to right across the web. As the web is moving forward, the carriage advances the feeder at half the speed, filling from left to right. When the web stops at the cycle, the carriage moves back to the left, and fills the remaining pockets while the web is static.
“You can’t use a chute feeder or brush box on an intermittent machine without the mobile carriage because no feeding would occur in the static portion of the cycle. In continuous-motion machines, you need the forward movement of the web to help drop or pull down the tabs,” he says.
Elizabeth Companies’ Combo feeder features three feeder formats that can be switched out in minutes for product change-overs.
“The versatility of these three distribution formats encompasses almost any tablet-feeding needs, providing a complete feeding solution with optimal performance. As we build our business as a blister tooling and feeder provider, the combo feeder differentiates us from our competitors, as an ideal solution for environments requiring frequent batch changes,” Spiegel says.
Feeders need to hit their fill rates without slowing down the blister line.
“The feeder will be the slowest part of the machine if you have to slow the process down for the feeders to be efficient,” says Brower. “With dedicated feeders, it may take time to orient the product in the feeder tube. You might starve the tube if you are running products that are not friendly. The product might not seat properly in the cavity or miss it altogether.”
“Sometimes static electricity rips it right out. Gel caps will take on the static charge that builds up in the plastic drop chutes causing the tabs to actually hang on the drop chute,” Brower says. “You can put static eliminators on the web to address this problem.”
Brown at Aylward concedes that tablet shapes and package formats will place limitations on feeding speed. But the XYZ feeder matches blister machine speeds in many cases.
“We meet any speed requirement up to 45–55 cycles per minute,” he says. “For higher fill rates, we can fill two indexes at once, for 80 cycles per minute. We also use our continuous-motion frame feeders to follow the web during the feeding cycle, which allows us to meet higher filling rates.”
FILLING WITH ROBOTS
Brower predicts that robotic filling will become more widely accepted as a method that provides higher accuracy and quality assurance.
“You need very few change parts with robots; the software provides the pick-and-place intelligence. We have invested a lot of resources on robotics with a recent focus on clinical trial packaging where a robot can accurately place multiple different drugs in the blister,” he says.
The vision system used to support the robotic picking also serves as an inspection tool, establishing that correct and intact tabs are picked before the product ever reaches the web. Pills can be prelaned or staged in trays to speed the robotic picking, he says.
Janssen Ortho prestages Risperdal MTAB tabs in trays for robotic handling on blister lines in its Guravo, Puerto Rico, facility for which Micron PharmaWorks supplied equipment and line component integration. The lines feature Micron’s TF2X thermoformer, based on a Klöckner CP-5 and Epson robots. Since a first line was installed in 2005, Micron PharmaWorks has supplied Janssen Ortho with two more lines, Brower says.
The type of blister film used can have an effect on feed rates and feeder format selection. “Tablet placement is affected by the target surface. The surface friction properties of the chosen material can impact accurate tablet placement. A fast blister machine is of little use if you can’t get the tablet in the cavity,” says Brown.
Klöckner Pentaplast (Gordonsville, VA) addresses this issue with its Pentapharm alfoil SG (Super Glide) films. The films feature enhanced slip properties that support faster feeding on filling equipment.
“The coefficient of friction of film has a significant impact on filling speed. And the faster you want to run the line the more resistance the film puts on the feeder. You don’t want slow filling to limit your total line speed,” says Daniel Stagnaro, business manager of pharmaceutical films.
The surface of the PVDC-coated films is modified to improve the coefficient of friction. SG films can increase machine speeds by 30%, and the films’ slip supports accurate placement of stickier forms such as soft gel tabs, Stagnaro says.
“If a film doesn’t have slip, the tab will have a tendency to stick to the cavity or be misplaced,” he adds. “Part of the cap could be left sticking outside the cavity, requiring added processes on the feeder to be sure the tab is accommodated,” Stagnaro says.