Sampling is a vital part of manufacturing.
You want to see if the manufacturer is in fact capable of producing the product that you have designed to the specifications that you have given.
We know to request a sample before committing to a volume order as part of our due diligence process.
The reason I have emphasized the word "part" above is that many of us fall into the trap of believing that a good sample means that we can assume manufacturing is going to be of equal quality and we can put a nice happy tick in our due diligence form to say we have thoroughly researched the supplier and their capabilities and we will have a container of premium quality products sometime in the very near future. No more work to do. Start sending the orders out ASAP!
Sorry to say manufacturing does not work this way. While the differences between samples and volume products may be subtle with some domestic manufacturers, this is often not the case when you manufacture offshore.
In either case samples are manufactured for the vendors benefit more than for the benefit of the customer. Look at them as a sales tool, not a representative product. "This is what we are capable of producing!" does not translate to "We will always produce this for you!" A sample is usually handcrafted and hand-carried through the entire production process. Hour after hour spent making sure everything is perfect and the customer is bound to be impressed and move forward with ordering. The manufacturing, QC and testing is often performed, verified and rechecked by senior management to ensure everything is done to the customer's requirements.
This process would become ridiculously expensive if employed in a volume production situation. So they show you the perfect sample and quote you for the reality of production. The management steps back after sample approval and allow the floor staff (on a much lower salary) to manufacture your product. These staff are capable of manufacturing or they would not have a job, but they are paid to produce high volumes not perfect products. If you have not carefully documented those aspects that are critical you the success of the product, and visually ensured that the floor staff are capable of following these procedures "to the letter" in a volume production situation, you really only have done a partial due diligence.
You should be on-site when the manufacturer is completing your first volume order. See how it is done in reality and know what concerns need to be addressed when they occur. Don't sit in your office and wait 6 weeks for a container of future landfill to arrive on your doorstep. Offshore manufacturing is not a venture that you can run successfully 100% from the safety of your office, sometimes it is necessary to go "down to the trenches" to make sure the vendor is working with your best interest at heart.