The consequences of taking a product’s manufacture out of the United States can mean life or death.

The potential to reduce manufacturing costs by moving to Asia, and in particular to China, has been a seductive lure over the last decade. Driven by business models that often prove less than reliable in the long view, companies have drastically altered sourcing strategies to take advantage of the supposed windfall that awaits anyone with the temerity to tackle the obvious logistical and cultural challenges of moving plants and equipment to such a different world.

Recent studies that have looked at the real costs of sourcing products in China and neighboring countries have shown that the economic benefits are not nearly as great as the initial analysis predicted, but most of these studies have focused on the hidden cost of the logistical support required to manage the supply chain from such a distance. There is another hidden cost, however, that involves maintaining control and quality assurance over the materials used to mold products.

Anyone who has been to Asia knows that the cultural atmosphere is one marked by a “can-do” attitude; whatever the customer wants is greeted with an affirmative response, even if the actual method to achieve the demand has not been worked out yet. Therefore, when it comes time to produce parts, if the specified material will not run or is unavailable, the processor will use something else rather than inform the customer of the obstacle. This can and does lead to serious consequences at the performance end. This case study tells the story of one product from the recreation market; in the next article we will profile a component in the small appliance arena.

Materials Not What They Seem

Because of confidentiality concerns, the product we are discussing can only be referred to as a piece of playground equipment. The specified material for the product was an ethylene-vinyl acetate (EVA) copolymer with a nominal melt-flow rate (MFR) of 6 g/10 min and a vinyl acetate content of 15%.

These two specifications automatically capture much of the desired performance profile of the material. The MFR reflects the average molecular weight of the polymer, which in turn governs properties like toughness and cut and tear resistance. The vinyl acetate content determines the balance between elongation and load-bearing properties, and also influences temperature-dependent behavior such as the ductile-to-brittle transition temperature and the softening point.

When the product began to split in the field, there were a number of concerns that needed to be addressed analytically. However, the first task was to determine what distinguished a good product from a bad one as it related to composition. Since the specified material was an EVA, the simplest and most cost-effective approach was to establish that both parts were made from an EVA and quantify the vinyl acetate content.

Because the vinyl acetate in an EVA decomposes at a substantially lower temperature than the ethylene-based portion of the polymer, the most straightforward technique for achieving this objective is thermogravimetric analysis (TGA). For those new to this column, this test evaluates a material through controlled decomposition.

Figures 1 and 2, opposite, show the TGA results for a good and a failed part, respectively. These graphs show weight loss as a function of temperature and use a derivative curve to highlight the beginning and end point of the various weight loss steps. The good part shows the characteristic early weight loss that establishes the presence and quantity of the vinyl acetate. The weight loss of 10.84% does not represent the exact vinyl acetate content. For reasons that are beyond the scope of this article—as well as the interest of most readers—this value must be multiplied by 1.43 to come up with the actual amount of 15.5%.

The failed part obviously contains no vinyl acetate; it is not an EVA. Figure 3 shows a DSC (differential scanning calorimetry) scan of the failed part that identifies the melting point for the failed part. This response is consistent with a low-density polyethylene (LDPE). While this establishes a difference in composition between the good and the failed part, it does not necessarily explain why the failed part did not perform. Given the application environment, an LDPE would be expected to perform adequately. The rest of the answer came, as it so often does, from the molecular weight. The MFR for the good product was just less than 7 g/10 min; for the failed part it was 56. This represents a massive difference in molecular weight with all of its performance implications.

It gets more complicated. Subsequently, two more parts were submitted for a good to bad comparison. Both of these parts also turned out to be LDPE. But the good part had an MFR of 4 g/10 min and the failed one came in just above 52. This analysis showed that we had at least three different materials in play: the specified EVA, a high-molecular-weight LDPE, and a low-molecular-weight LDPE. Two of the three appeared to make parts that worked in the field.

The Blame Game

Now, here’s the punch line and the real economic impact. Somewhere in a warehouse in this country sit thousands of these parts, waiting for assembly, packaging, and shipping. The cost of holding this product as a component in inventory is bad enough. The failure to realize the revenue that could come from selling the finished assembly is worse.

But the real hit comes from trying to dispose of all of this product without spending tens or hundreds of thousands of dollars. The one thing that is virtually guaranteed is that the financial advisors who advocated moving the manufacturing offshore are nowhere to be found, and the accountants generating the financial statements are not assigning these costs to their analysis of the success of this venture.

The lesson here is that when manufacturing takes a low-cost route, it must factor in some costs for prevention. Verifying composition and performance, not just on the first article but on an ongoing basis, will save in the long run. However, the mentality that seeks dramatic cost reductions is rarely aligned with a disposition to spend money on something so seemingly frivolous as polymer testing. The unspoken expectation is that these moves to low-cost manufacturing centers are all upside. But there are costs to the business of cost reduction, and most of them are hidden.

For those who believe that situations like this one can all be managed from documentation-driven systems, let me assure you that offshore manufacturers will gladly provide you with certifications for the material that is on the print while still making the parts out of whatever is available.

The final insult in our scenario is that failure of this product can result in serious injury or even death, and the object of this injury will almost certainly be a child. Anyone who has ever been involved in a product liability case where the victim is a child knows that there is no tenacity like that of a parent whose child has been hurt, and the lawyers know this.

When it comes time to settle, our product liability laws do not extend to the countries where these parts have been made, and there should be no expectation that the considerable costs associated with these litigations and their outcomes will be shared by the molder.

Contact Information Dickten & Masch Mfg. Co. Nashotah, WI Mike Sepe (262) 369-5555, ext. 572 dmlab@execpc.com www.dicktenplastics.com