A purported &34'mold engineer drawing&34' of an iPhone 5 from earlier this month.

Those who were expecting Apple to ship a follow-up to the iPhone 4 this summer may be in for a longer wait than usual.

A new report from Japanese Mac blog Macotakra says Apple is behind its usual schedule of ordering parts that go into the manufacturing process for the device. That change in pace could result in Apple shipping out a phone a few months later than the June time frame for the previous two models, and July for the iPhone 3G.

AppleInsider, which picked up on the report this morning, notes that the later timing would result in the next iPhone missing Apple's fiscal 2011, which concludes on September 24 this year.

Along with the timing news, Macotakra's report, which is based on its sources in China, notes that Apple has still not committed to changing the materials used on the back of the iPhone from glass to metal. Rumors of such a change had first cropped up in March, with a follow-up report a few weeks later by 9to5Mac that said Apple was indeed testing out prototypes of future iPhone designs with metal backs.

That move had originally been said to help set the device apart from the iPhone 4 since there were many other design similarities, as well as cut down on shattering incidents for dropped phones.

If the rumor proves to be true, it would likely be unwelcome news to those who had been banking on upgrading their phones this summer. But with expectations that Apple now has to juggle both GSM and CDMA versions of the device, possibly implement a near-field communications chip (and the infrastructure that goes with it), as well as cook up the next major release of iOS, there are plenty of moving parts that can push back that time frame.