Question

1. (15%) Describe the difference between a pull (Kanban), push and CONWIP production systems.

Answer 1

Difference between a pull, push and CONWIP production systems

The original meaning of up and pull, as used in operations management, logistics and supply chain management.

In the pull system production orders begin upon inventory reaching a certain level, while on the push system production begins based on demand (forecasted or actual demand).

The CONWIP(Constant Work in Progress) is a hybrid between a pure push and pure pull

With a push-based supply chain, products are pushed through the channel, from the production side up to the retailer. The manufacturer sets production at a level in accord with historical ordering patterns from retailers. It takes longer for a push-based supply chain to respond to changes in demand, which can result in overstocking or bottlenecks and delays (the bullwhip effect), unacceptable service levels and product obsolescence.

In a pull-based supply chain, procurement, production and distribution are demand-driven rather than to forecast. However, a pull strategy does not always require make-to-order production. Toyota Motors Manufacturing is frequently used as an example of pull production, yet do not typically produce to order. They follow the "supermarket model" where limited inventory is kept on hand and is replenished as it is consumed. In Toyota's case, Kanban cards are used to signal the need to replenish inventory.

A supply chain is almost always a combination of both push and pull, where the interface between the push-based stages and the pull-based stages is sometimes known as the push–pull boundary. However, because of the subtle difference between pull production and make-to-order production a more accurate name for this may be the decoupling point. An example of this would be Dell's build to order supply chain. Inventory levels of individual components are determined by forecasting general demand, but final assembly is in response to a specific customer request. The decoupling point would then be at the beginning of the assembly line