A number of market trends are affecting the types and sizes of packaging being developed for motor oil, Manderfield told the gathering in Charleston, S.C. For example, were seeing a move away from single-quart bottles to larger containers. This shift is small right now, but he sees the trend continuing to favor multi-quart packages.

Pointing to data from Nielsen, he noted that one-quart containers are still popular. And sales of quarts did inch up in total units sold from June 2011 to June 2012 – but sales of five-quart jugs grew even faster over that time, posting a 9.2 percent gain in the number of units moved.

Beyond size, other factors are at work, too. Suppliers are also using different aesthetic elements to attract attention in the marketplace, Manderfield said, including transparent bottles, metallic colors, brighter colors, textures and gradients.

International suppliers are also influencing bottle design. Ive found that international companies are leading the trends. One trend in Europe is a larger cap, he added. Creative bottle designs provide opportunities for different label designs, all to differentiate products on the shelf.

Design Variables

Manderfield then described the key factors that go into designing motor oil packaging. There are many different layers to consider, he said. We have to consider the consumer, the retail environment, the filling process, and how the container gets into the supply chain. Tools used in this analysis include conventional laboratory testing and finite element analysis (FEA) on the computer.

The variables to consider in any bottle design are what resin to use, the types of molding machines that will be employed, and the capabilities expected of the bottle, Manderfield said. We use a variety of resins in our bottles, including high-density polyethylene (HDPE), polypropylene (PP), polycarbonate (PC), poly-ethylene terephthalate (PET), low-density poly-ethylene (LDPE), and co-polyester, as well as custom and multilayer materials.

Types of bottle-molding equipment include rotary wheel, conventional and long-stroke shuttle, reciprocating, accumulating head (for polycarbonate), single-stage (for polyethylene terephthalate), and two-stage blowmolding machines (injection and stretch).

Finally, the expected capabilities of a bottle can encompass decoration, the amount of post-consumer recycled material, high environmental stress-cracking resistance, oxygen barriers, chemical barriers, and creative design and development.

Manderfield reminded the attendees, One thing you have to think about when designing a bottle is not to handle the empty container. You have to fill it with liquid because that gives you the true nature of what the bottle will feel like.

Handling the Consumer

What were seeing in the last several years is packaging with more than one handling point if its a multi-quart bottle, Manderf ield said. Two-and even three-handle packages are becoming more common, especially as containers go up in scale. We have to remember multi-quart packages can contain up to five liters of oil, and that can be heavy. Designers must consider who might be handling the bottle when determining the number of handling points. Should the handle be at the top, or slant along the side, for ease and control?

Besides adding handles, Manderfield noted, another thing you can do is add a crevice in the base of the bottle to assist the user in pouring the oil. The prime design consideration with this element is to avoid a mold equipment hangup that might slow down bottle production. Another issue to guard against is thinning of the wall, which might create a weak spot in the bottle.

Another popular convenience on many bottles today is a view stripe that lets users know how much fluid they are putting in the crankcase or have remaining in the bottle. There are many ways to incorporate this element. Our approach is to make the mold and do some trial runs. Then go back and add the engraving and units to the package, said Manderfield.

Then there is the so-called no-glug feature. Many years ago, we were working on the problem of pouring bleach without splashing it all over, he recalled. The problem was solved by adding a pinched-off neck area that lets liquid pass out while let-ting air in. This feature has been heavily borrowed and transformed over the years for various types of bottles and products.

Is It Shelf-friendly?

The next thing to consider is what retailers want. We go shopping a lot in different types of stores to see what the retail environment is like, said Manderfield. It could be a small convenience store, pharmacy, automotive parts store, or big-box store. We check how the shelves look, how they are arranged and how products are displayed.

All these things add up, and constrain what a package can look like and its footprint and size. One important consideration is that retail store shelving is set in place and not easily changed in height or depth. So we cant arbitrarily change bottle design, because it may not conform to existing shelf constraints, he added.

Manderfield explained that his team is constantly visiting stores to see whats new. For example, endcaps [shelving units at the ends of the aisles] are being set up, and gravity racks are being used in many places. This helps us to see if there are any issues, such as bending of the bottles in the rack.

Consolidated Container also considers the cases that the bottles are shipped in, using package design software which can reverse-engineer the bottle footprint based on the desired shipping carton.

Any time were doing a redesign, we have the opportunity to tweak the footprint, Manderfield added. This is especially true in the redesign of older stock bottles. Thirty years ago, companies were not considering packing efficiencies like they are now. We have software that can help us optimize bottle and case size, pallet load and trailer load to ship product most efficiently.

In general, round packages do not pack efficiently. Even square bottles provide some packing inefficiency, so engine oil bottles (and many others) tend to be an oblong shape. Weve found that every package has a sweet spot that allows the most efficient packing in a case and on the shelf, Manderfield stated.

Dont Slow the Filler

Simply put, filler efficiency is king. If we do a pretty design and it only fits in the filler at 50 percent efficiency, that doesnt solve anyones problems, he continued. So we have to go back and look at the footprint again.

Typically, the filling equipments only adjustment factor may be bottle height – and rather than slowing down the filler, it may be better to retool the bottle.

One trick we have for adjusting volume without harming filler efficiency involves making whats known as a shim height adjustment. Here, the heel of the bottle can come off the mold and a segment be insert-ed or removed from between the heel and the rest of the bottle, Manderfield said. The new bottle can be either shorter or taller, but the footprint has not changed. These are relatively minor changes in terms of time and expense.

A vertical adjustment may not be the only needed adjustment to the bottle. Designers can also put in a different type of heel. This is common because when redesigning to reduce bottle weight, the bottom might flex too much. So the heel has to be redesigned to strengthen it.

A final consideration is to look at the types of testing the bottle must pass. For example, the UN drop test is required for United Nations certified packaging, and is one of the most severe tests. Here the prototype carton, full of filled containers, is held at an angle and dropped on a corner. The UN protocol allows for some crushed areas, but the bottles cannot leak.

Help from the Computer

One tool package designers use, as mentioned above, is FEA, finite element analysis. In this analysis, we import the bottle design into a three-dimensional computer aided design program, which converts the design to a mesh pattern, Manderfield related. Then we assign material properties to the design, related to the exact grade of the resin used.

Resin properties can change as the material is heated, runs through an extruder and is blown into shape. So designers test bottle prototypes and samples, and use that test data for the material properties loaded into the CAD software.

Then, we add wall thicknesses and boundary conditions, Manderfield said. Finally, we apply a load to the top of the bottle, watch it deform, and analyze the results. The illustration at left shows some typical FEA results, and the steps taken to improve the design.