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IMM's Plant Tour: Molding precision meets human genome exploration

August 1, 2001

11 Min Read
IMM's Plant Tour: Molding precision meets human genome exploration

IImagine leaping from a 10-ft-high diving board and plunging headfirst into an open manhole without hitting the rim. Now imagine performing this flawless dive of yours 1536 times in a row. Impossible? Perhaps. But one new captive molder is challenged by mold and part requirements that are equally unforgiving. The pipettes it molds, also called "tips," are used in the automated liquid handling systems it builds for biotech research projects around the world, including genetic research. The margin for error in the dimensional conformity of its tips is, like your dive, zero. 

Rick Carl, the former owner and current president of CCS Packard Inc. (Torrance, CA), is an archetypal all-American inventor-entrepreneur. He was a major player in revolutionizing the life-science research industry. Carl developed fully automated, modular workstations for pipetting microliter and submicroliter volumes of aqueous, organic, and protein suspension samples into multicavity reservoirs called microplates, used to transport samples through further processing. Filling the small microplates used to be done by hand. 

The speed, precision, and accuracy of Carl's systems resulted in widespread acceptance of his technology. Three years ago, to better control growth, he sold his company, then called Carl Creative Systems, to a global biotech giant, Packard BioScience Co. (Meriden, CT). But customer demands were growing right along with the technology's popularity. Originally there were 96-well microplates, but then 384- and 1536-well plates were needed. Carl had been outsourcing pipette molding, but as well densities increased and tip tolerances contracted, the percentage of reject parts expanded. 

He has always been a believer in the benefits of vertical integration. With zero molding experience, Carl put up his own money, drew on the talents of his human resources, and opened an operation in March 2000 that molds pipettes certified to dive into every tight-tolerance well on a microplate every time—even 1536 of them—without hitting a single rim. Impossible? It's a leap of faith. Let's tour. 

Unforgiving Dimensions 
Carl and Daniel Dechert, product manager and a third-generation mold designer respectively, greet us in the CCS Packard conference room to better acquaint us with the parts the company molds. The pipettes are molded of a 100 percent virgin medical PP. Each is designated by the maximum volume of microliters it can hold (a P30 tip can hold up to 30 microliters of liquid). CCS Packard molds different size pipettes for 96-, 384-, and 1536-well plates. Part weight of its P10 pipette, its smallest, is .0738g. 

Tip size, concentricity, length uniformity, and sealability are among the chief requirements that must be met to ensure mistake-proof automated dispensing. Take sealability: CCS tips use a direct mechanical press-fit between the individual pipettor dispense head and tip seal surface. When, say, 384 pipettes are racked and ready to load into a dispense head, the difference between the seal diameters of all 384 pipettes must be within ±.00025 inch (±6.35 µm). Also, if tip seal surfaces are out of round the seal will fail. 

Or, take straightness and concentricity: The concentricity/straightness of a .031-inch OD P10 tip is .007 inch TIR (total indicator runout) along its entire center axis. For a 384-well microplate, each pipette is subjected to less than 2 lb of load pressure by the dispense head. All of the tips must hit their respective wells without hitting the walls of the microplate. 

"Our tolerances are plus or minus zero," Dechert jokes. "But seriously, with those kinds of diameter tolerances, we are not trying to hit a specific number. We just want all 384 pipettes in one rack to have the same seal shape. Our spec is no more than one bad pipette in 38,400. On a fully automated machine, one load of 384-format pipettes may dispense into 1000 microplates. In such cases, one bad pipette will cause 1000 errors. Our customers depend on our quality." 

CCS Packard's standardized Class 100,000 molding, testing, inspection, and packaging cleanroom is exclusively dedicated to the production of pipettes used in the microplate processing systems the company builds for biotech research.

CCS Packard molds different size pipettes for 96-, 384-, and 1536-well microplates. Each must dive into tight-tolerance wells every time without hitting a single rim. The P235 tip (A) is designed for a 96-deepwell microplate, while the P50 tip (B) works for the standard 96-well plate. The P30 tip (C), which has a .79-mm tip OD, is for a 384-well plate. The smallest of the pipettes at .0738g is the P10 tip (D) used for 1536-well plates.

Diving Into Molding 
Molding is done in a positive-pressure, Class 100,000 cleanroom. The room is airy, with 14-ft-high subceilings concealing Hepa filters; and it is immaculate, right down to its polished concrete flooring. It also is standardized and hybridized. 

For example, all of its injection molding machines are 60-metric-ton models in Sodick's EH series of hybrid servohydraulics, each featuring a hybrid injection unit with an all-electric plasticating fixed screw and a hydraulic plunger. Each hybrid press is equipped with a hybrid servopneumatic Yushin robot. Each machine is dedicated to molding a specific size pipette, facilitating single-piece flow. The machine cells are on one side of the room. Testing, inspection, and packaging are on the other. 

Adjacent to the molding room are auxiliaries, inclucing a Thermal Care chiller and equipment from Maguire, Autoload, and Nucon. 

The Sodicks are positioned at a 45° angle. This allows customers to easily see their tips being processed by looking through a bulkhead window into the molding room, which inspires greater customer confidence, according to Dechert. 

"Molding was getting in the way of our selling our main line of equipment," Carl explains. "No tips, no product—no tires, no car." He says his company was working with custom molders who were "old established companies using old established molding equipment, who were more interested in issues like mold costs than consistent quality." 

"But we learned from them," he adds. "They taught us what not to do." 

Robotic Certified Quality 
CCS Packard has found cavity segregation to be instrumental in ensuring the dimensional conformity of its tips. "In all multicavity tooling, part dimensions will vary in some form from cavity to cavity. There is no such thing as a universally perfect 'steel condition,'" Dechert explains. Rather than racking all the tips from one or more molds together, CCS pipettes are segregated and racked by mold cavity. All the tips in a single rack are from the same cavity. 

Robot integration is as essential as cavity segregation. The tips are removed by robots and are directly inserted into their racks via proprietary cavity-isolation conveying methods. Robotics help ensure that the tips do not come into contact with any contaminated surface, or with any other tip, from molding through packaging. 

CCS Packard calls its products "Robotic Certified Tips." They are certified by cavity segregation and robotic extraction to help support mistake-proof, high-throughput liquid handling applications. To further ensure that pipettes are ready, the company tests them on its own liquid handling systems on the molding room floor. 

The tips then must pass multiple inspection tests, including visual inspection, to verify precision. Still, the tests are not all that complicated. CCS Packard believes that its production system itself is robust enough to produce tips that will hit a specific microplate well every time—even 1536-well plates with well diameters that are .069 inch, ±.001 inch—obviating the need for more testing. 

CCS Packard's inventiveness is evident on the shop floor. For example, it has designed its own temperature controller.

The eight-cavity shot weight for the CCS P30 pipette is 2.146g (.07569 oz), including the runner. Sodick's two-stage injection unit reportedly helps CCS Packard reduce part weight variations 10 times vs. a general purpose press. 

Vertically Integrated 
Carl has nothing but praise for the performance of his Sodick molding machines. "I can't begin to tell you how much help Sodick has given to us. We wanted to improve the degree of predictable accuracy in our tips. Other molders with GP molding machines could not make our tips. They would not accept the tolerances. The machine does make a difference. 

"The Sodicks are very repeatable," Dechert explains. "Part weight deviation control is 10 times better than what we saw from our former vendor's machine." CCS Packard was the first U.S. customer of Sodick EH Series presses (20 to 180 metric tons). 

CCS Packard enjoys very close relationships with all of its suppliers. Still, as previously mentioned, Carl is an inventor. Dechert is equally inventive. Both have designed and/or built systems to improve productivity. In fact, Dechert has even helped Sodick re-engineer its already expertly engineered molding machines. 

For example, he wanted the shot size to be 80 percent of the plunger stroke on Sodick's two-stage injection unit. After Sodick delivered a right-sized injection unit, Dechert talked Sodick into equipping the CCS Packard presses with dual injection unit cylinders to better hold the injection unit forward during high-speed plunger injection. Dual cylinders are now standard on EH Series machines. 

CCS Packard also develops solutions on its own. It built its own beside-the-press mold cranes. All of its EOATs are designed and built in-house, as are its proprietary cavity-segregation conveying systems. What's more, CCS Packard even designed and built its own temperature controllers for its molds and hot sprues. 

Control Speeds Invention 
Speaking of hot sprues, most of CCS Packard's hot sprue, cold runner, dual subgated molds are eight-cavity, unit-frame tools with multilevel cooling. They are all stainless steel with H-13 cores and 420 cavities, designed in-house and built with a dual ejection system. 

Dechert describes the molds as being "simple, reliable, and built specifically for robotic extraction." Like Carl, he credits the Sodick presses for making the molds look good. "The Sodicks are able to fill all the cavities consistently. We don't even have an occasional short shot." The company also has had good success with 16-cavity molds and has not ruled out 32. Still, its more difficult tips are molded in low-cavitation tooling. 

Referring to his new injection molding venture, Carl wraps up by saying, "Now I am in control. When you try to subcontract such work out, you are dependent on outside sources. It is better to be dependent on yourself. We also make more money being vertically integrated. 

"But the main reason is not dollars," he concludes. "Integration gives us better control over our technology and the ability to respond faster to market demands. We're inventing new products all the time. Now, we can make them in months, rather than in years." 



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