The German-based firm appointed the pair last month, with Ehl based in Germany, and Shoulders working from North America.
Ehl has been with the company for eight years and was previously Chief Executive Officer (COO).
Shoulders was president of Oystar North America.
The group divested its process division at the beginning of the 2011 to concentrate on packaging machinery for the food, dairy, pharmaceutical and cosmetics.
Ehl said: "The change in management will not alter the successful Oystar strategy. We will continue to focus on the packaging business in the future, pursuing our growth strategy."
Shoulders said: "We continue to be ambitious. With the consistent continuation of our product strategy we aim to achieve sales of €500m by 2015 with a considerable double-digit EBIT margin."