Ring Can Corporation Saves Design Time for Plastic Containers
ZW3D has helped us cut the design cycle by at least half.
— Ring Can
Ring Can Corporation has a history of innovative packaging, making it one of the largest and fastest growing container manufacturers in North America. For example we introduced efficient plastic containers for edible oil – and in the process, converted the entire industry from metal cans to lighter weight plastic containers. Among our brand names are EZ-FLO, TUF-PAK, SAF-T-FLO and EZ-PAIL, used by industries that include food, industrial chemical and crop protection markets. Behind all our packaging solutions lies a determination to design the lightest plastic containers in the industry without compromising package performance. Our customers include food and personal care giants such as Procter&Gamble, Cargill and Dean Foods.
I use ZW3D Vision from Varimetrix Corporation for my designs and believe that it has significantly reduced our design cycle time – by as much as 50%.
Plastic bottles may look very straightforward, but design difficulties often arise from their shapes – particularly the shapes of bottles with handles. Most bottles feature a sculpted look to enhance shelf appeal. To achieve an attractive, sculpted look along with the strength needed I want to switch from solids – as good as solids are today – to surfaces, to get blends and transitions. I’ve found that with ZW3D Vision, it’s easy to go back and forth between solids and surfaces, or to make a surface and then blend it into a solid.
For example, I recently designed a bottle for holding cooking oil. The bottle has a base that measures between five and six inches across, and a height of 11 inches. Along with many facets, it has a handle that blends into the bottle’s neck to avoid “glugging” when a user pours oil. Glugging can be prevented by creating a small shelf in the neck section that restricts the displacement of oil by air.
One of the most important considerations in designing a container like this one is manufacturability. We generally use blow molding to manufacture these bottles, and you need the proper draft angles to get the bottle out of the mold without tearing or distorting it.
I design the rectangular bottle in solids from the bottom up, paying particular attention to a wide recessed area all around the bottle for the customer's label. The recess protects the label. Shoppers generally avoid damaged labels, and as the bottle will be shipped packed in a box with four to six others, the labels can get scuffed if they aren’t recessed.
When I get to the point where I’ve designed a rectangular solid bottle with a round neck, I cut into the rectangle to create the handle. At this stage, I encounter sections with facets and have to angle the handle so that it doesn’t come straight out of the rectangle, because if it did, the manufacturing people couldn’t get it off the mold. I need to picture the inside part of the hole the handle comes out of, and make a profile to create positive draft for molding. I’m still using solids, and I put in two different draft angles. Because I know the shape and angle of a handle that will work in the molding process, I can sketch and extrude them out of the bottle.
At this point, I shift to surface modeling. Where the handle joins the bottle at the lower end, I use the surface-surface blend feature of ZW3D Vision with drive curve to get wrap-around and blend. These commands tell the surface blend to wrap all around the handle and blend the surface between the body of the bottle and the handle. The radius varies, so to blend the surface all around, I use ZW3D Vision’s variable fillet blend. After that, I can go into the handle and bottle and trim the mating surfaces back to what I laid in during the surface-surface blend.
I explode the surfaces out of the solid model in ZW3D Vision, and using the edge of the surface I trim each back to the corresponding edge. That trims them to the blended surfaces. ZW3D can join surfaces automatically, but I prefer to turn off the automatic feature to gain more control.
It’s not necessary to use surfacing in areas where three or four surfaces come together in a fillet, and I like automatic creation of fillets in ZW3D. When you use the automatic fillets, you turn control over to the software and in some cases the results may not be exactly what you want. I check first to see what the software does when it creates a fillet. If I like the result, I keep it. If not, I’ll go to surfaces to get the fillet detail just the way I want it. For example, sometimes with automatic fillets, you can get sharp corners. In plastic bottles, sharp corners create very thin areas that will be weaker than you want. In the case of the oil bottle, I needed to blend at the top of the handle of this particular join, so I laid in the fillets using surfaces.
As usual, in making bottles, I have to keep the manufacturing process in mind. In critical areas, such as the fill line in the container and whether the product either reaches the line or overfills beyond the line, I have to use my experience with the molding process. In this case, I like to switch back and forth between surfaces and solids. I need solids to get certain size and overfill capacities and to get the fill line in the right place. And I need surfaces to keep the attractive look of the bottle.
We don’t design our own molds, but rather they go to a mold vendor who works from the product design. In blow molding, I am essentially building a cavity, and the volume is critical. I must have that correct if I want to get the fill line in the right place.
The parametrics use in ZW3D Vision works differently from other programs. Because volume is so critical in plastic bottles, I need to have some way to make changes quickly if, for example, the particular bottle is made of light plastic that bulges out when filled, and so doesn’t appear to hold product all the way up to the fill line, or where the cavity is too small to hold all the product and it overflows. In ZW3D Vision, I can make changes at any point in the history and have the change carry through the rest of the subsequent history. I often find this capability necessary to make sure of overflow capacities, which can take some going back and forth.
It used to be that, after finding out what a customer wanted, I would draw designs in 2D, send the sketch to the customer, and repeat that process until the customer was satisfied. That could take up to a week. Nowadays, I can create a complete design in a day most of the time, and then just email the IGES file to the mold shop and get a prototype in three days. ZW3D Vision has helped us cut the design cycle by at least half, and the robustness of the software helps us save even more time – and we derive cost savings relative to the amount of time we save.
We’ve improved quality as well, because the mold maker can create the exact mold for a particular bottle right from the designs produced using ZW3D Vision. I’m currently looking forward to ZW3D Vision Version 4, where we can place images directly onto a surface from a picture. For example, with an electronic image of a cat, we can place an embossed image of a cat directly on the surface of a cat litter container for one of our customers.
Note: VX CAD/CAM software and technology has been acquired by ZWCAD Software Co., Ltd. VX CAD/CAM has been rebranded as ZW3D. All the testimonials of ZW3D refer to its predecessor.