Second type is Dependent Demand Inventory the main advantage is that

Second type is Dependent Demand Inventory - the main advantage is that dependent demand parts can be utilized to buffer the schedule against uncertainty. It allow scheduling to be more balanced and stable. All of this is managed through MRP systems (Material Requirements Planning). If you want to closely review the system there is too much researchers who reviewed it. (Panisset B 1988) (10) (Flapper 1994) (11)

Relations between inventory control (policies) and PPC should be more detail and narrowly investigated to satisfy the customer service level

Nowadays remanufacturing is one of the most growing part of manufacturing industry despite of it economic and social benefits remanufacturing connected with many different challenges.

(APSRG, 2014 (12)). ERN (European Remanufacturing Network 2015 (13)) in 2015 underlined the 10 remanufacturing challenges experienced by hundred eighty-eight remanufacturers. In this chapter, we are going to speak about them.

As we know that manufacturing is very difficult industry due to it very high number of uncertainties (external and internal). (Hammnod R. 1996 (14))

According to the different literature review and resources, we can tell that there is three level models of challenges:

1. Process level challenges ( remanufacturing process)

2. Industry level challenges (challenges related to remanufacturing industry )

3. System level challenges (remanufacturing system)

Industry level challenges - thus challenges were analyzed from different perspectives like environmental and economic, they can be code as law and environmental regulations. Industry level challenges are divided by 3 categories - 1. Labor costs versus product value 2. Variable inflow of cores 3. Skeptical customer perception (Guidat, T., Uoti, M., Tonteri, H 2015 (15)).

System level challenges - thus challenges were analyzed in a perspective of product lifecycle system (costumers, engineers, designer, service etc.

). The challenges revealed in the SLC usually between different product life cycle

Process level challenges - there is too much researches and reviews to reveal challenges considered to develop efficient operations. (Steinhilper, 1998; Guide, 2000; Van Nunen Jo and Zuidwijk, 2004 (16))

Companies have to overcome the challenges and to do it there are some developed suggestions. To overcome remanufacturing challenges there is seven lean-based improvements that mainly influence on lead-time reduction .There are these suggestions

1. Standard operations

2. Teamwork

3. Kanban

4. Continuous flow

5. Layout or continuous flow

6. Supplier partnership

7. Employee cross-training

Applying these seven improvements will help the company to decrease the lead-time (about 90 percent lead - time reduction)

Disassembly - is a very necessary process, which differ remanufacturing from traditional manufacturing. "Remanufacturing is a unique process where used products are returned to a good perfect (as new) condition and have to provide same level of performance as new product. (Thierry, 1995 (17)). There is some processes in manufacturing like inspection, reconstructing, disassembling, cleaning, and sorting.

As we know, the main problem in manufacturing processes is uncertainty and remanufacturing is not an exception. Guide 2000 (18) was reviewing that issue and find out that uncertainty is divided by 3 classes:

· Existing uncertainty : Customer order , Supply of cores

· Uncertainties that appears during the process (disassembly) : Sequence of uncertainty , choose of repair method, disassembly level)

· Uncertainties that appears after the process (disassembly) : new materials and parts buy, product sell price, amount of inventory

There is a big number of researches and reviews in internet about disassembly area but most of them are fully theoretical with adding of malingering and numerical modeling. (Filo and Junior 2012)

Most of these researches includes disassemble inside of remanufacturing industry (not separately).

The process method of disassembly usually differs from the size of the company. For example in the small companies, the process is more manual than in big one where the process is more automated. To support the automated way Simolowo 2011 reviewed how companies manage sorting of cores to remove those which can damage the automated process. Westkamper 1999 (19) reviewed that disassembly process should be changeable to help companies to conform to market changes (lose